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Interrupted S NAr-Alkylation Dearomatization. JACS AU 2024; 4:1118-1124. [PMID: 38559710 PMCID: PMC10976598 DOI: 10.1021/jacsau.3c00813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/29/2024] [Accepted: 01/31/2024] [Indexed: 04/04/2024]
Abstract
Dearomatizations provide powerful synthetic routes to rapidly assemble substituted carbocycles and heterocycles found in a plethora of bioactive molecules. Harnessing the advantages of dearomatization typically requires vigorous reagents because of the difficulty in disrupting the stable aromatic core. A relatively mild dearomatization strategy is described that employs lithiated nitriles or isocyanides in a simple SNAr-type addition to form σ-complexes that are trapped by alkylation. The dearomatizations are diastereoselective and efficient and rapidly install two new carbon-carbon bonds, one of which is a quaternary center, as well as nitrile, isocyanide, and cyclohexadiene functionalities.
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2
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Synthesis of β,γ-Unsaturated Aliphatic Acids via Ligand-Enabled Dehydrogenation. J Am Chem Soc 2023; 145:20951-20958. [PMID: 37698388 DOI: 10.1021/jacs.3c06423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2023]
Abstract
α,β-Dehydrogenation of aliphatic acids has been realized through both enolate and β-C-H metalation pathways. However, the synthesis of isolated β,γ-unsaturated aliphatic acids via dehydrogenation has not been achieved to date. Herein, we report the ligand-enabled β,γ-dehydrogenation of abundant and inexpensive free aliphatic acids, which provides a new synthetic disconnection as well as a versatile platform for the downstream functionalization of complex molecules at remote γ-sites. A variety of free aliphatic acids, including acyclic and cyclic systems with ring sizes from five-membered to macrocyclic, undergo efficient dehydrogenation. Notably, this protocol features good chemoselectivity in the presence of more accessible α-C-H bonds and excellent regioselectivity in fused bicyclic scaffolds. The utility of this protocol has been demonstrated by the late-stage functionalization of a series of bioactive terpene natural products at the γ-sites. Further functionalization of the β,γ-double bond allows for the installation of covalent warheads, including epoxides, aziridines, and β-lactones, into complex natural product scaffolds, which are valuable for targeted covalent drug discovery.
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3
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Copper-Catalyzed Radical Enantioselective Carbo-Esterification of Styrenes Enabled by a Perfluoroalkylated-PyBox Ligand. Angew Chem Int Ed Engl 2022; 61:e202202077. [PMID: 35510403 DOI: 10.1002/anie.202202077] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Indexed: 12/17/2022]
Abstract
Chiral lactones are found in many natural products. The reaction of simple alkenes with iodoacetic acid is a powerful method to build lactones, but the enantioselective version of this reaction has not been implemented to date. Herein, we report the efficient catalytic radical enantioselective carbo-esterification of styrenes enabled by a newly developed CuI -perfluoroalkylated PyBox system. Simple styrenes have been converted to useful chiral lactones, whose synthetic applications are showcased. Mechanistic studies reveal that this reaction is a rare example of an efficient ligand-decelerated system, in which the ligand decelerates the reaction, but the reaction is still efficient with reduced amounts of ligand. This uncommon catalytic system may inspire further consideration of the effect of ligands in asymmetric catalysis.
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4
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Catalytic enantioselective 5-endo-bromocycloetherification of unactivated cyclic alkenes. Tetrahedron Lett 2022. [DOI: 10.1016/j.tetlet.2022.153906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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5
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Development of Anionic Phase-Transfer Catalysts for Asymmetric Fluorinations. J SYN ORG CHEM JPN 2022. [DOI: 10.5059/yukigoseikyokaishi.80.632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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7
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Catalytic Desymmetric Dicarbofunctionalization of Unactivated Alkenes. Angew Chem Int Ed Engl 2022; 61:e202111598. [PMID: 35286744 DOI: 10.1002/anie.202111598] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Indexed: 12/16/2022]
Abstract
The construction of multi-stereocenters by a transition metal-catalyzed cross-coupling reaction is a major challenge. The catalytic desymmetric functionalization of unactivated alkenes remains largely unexplored. Herein, we disclose -a desymmetric dicarbofunctionalization of 1,6-dienes via a nickel-catalyzed reductive cross-coupling reaction. The leverage of the underdeveloped chiral 8-Quinox enables the Ni-catalyzed desymmetric carbamoylalkylation of both unactivated mono- and disubstituted alkenes to form pyrrolidinone bearing two nonadjacent stereogenic centers in high enantio- and stereoselectivitives with broad functional-group tolerance. The synthetic application of pyrrolidinones allows the rapid access to complex chiral fused-heterocycles.
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8
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Copper‐catalyzed radical enantioselective carbo‐esterification of styrenes enabled by a perfluoroalkylated‐PyBox ligand. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202202077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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9
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Catalytic Desymmetric Dicarbofunctionalization of Unactivated Alkenes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202111598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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10
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Mechanistic Details of Asymmetric Bromocyclization with BINAP Monoxide: Identification of Chiral Proton-Bridged Bisphosphine Oxide Complex and Its Application to Parallel Kinetic Resolution. J Am Chem Soc 2022; 144:3913-3924. [PMID: 35226811 DOI: 10.1021/jacs.1c11816] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The mechanism of our previously reported catalytic asymmetric bromocyclization reactions using 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP) monoxide was examined in detail by the means of control experiments, NMR studies, X-ray structure analysis, and CryoSpray electrospray ionization mass spectrometry (ESI-MS) analysis. The chiral BINAP monoxide was transformed to a key catalyst precursor, proton-bridged bisphosphine oxide complex (POHOP·Br), in the presence of N-bromosuccinimide (NBS) and contaminating water. The thus-formed POHOP further reacts with NBS to afford BINAP dioxide and molecular bromine (Br2) simultaneously in equimolar amounts. While the resulting Br2 is activated by NBS to form a more reactive brominating reagent (Br2─NBS), BINAP dioxide serves as a bifunctional catalyst, acting as both a Lewis base that reacts with Br2─NBS to form a chiral brominating agent (P═O+─Br) and also as a Brønsted base for the activation of the substrate. By taking advantage of this novel concerted Lewis/Brønsted base catalysis by BINAP dioxide, we achieved the first regio- and chemodivergent parallel kinetic resolutions (PKRs) of racemic unsymmetrical bisallylic amides via bromocyclization.
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11
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Enantiocontrol over Acyclic Quaternary Stereocenters by Acylative Organocatalyzed Kinetic Resolution. European J Org Chem 2022. [DOI: 10.1002/ejoc.202101475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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12
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Abstract
Catalytic asymmetric halocyclization of olefinic substrate has evolved rapidly and been well utilized as a practical strategy for constructing enantioenriched cyclic skeletons in natural product synthesis.
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Non-Enzymatic Kinetic Resolution and Desymmetrization of α-Quaternary Carboxylic Acids via Chiral Bifunctional Sulfide-Catalyzed Bromolactonization. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2021. [DOI: 10.1246/bcsj.20210347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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14
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Asymmetric Bromoaminocyclization and Desymmetrization of Cyclohexa-1,4-dienes through Anion Phase-Transfer Catalysis. Org Lett 2021; 23:8153-8157. [PMID: 34623166 DOI: 10.1021/acs.orglett.1c02817] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The catalytic enantioselective desymmetrizing bromoaminocyclization of prochiral cyclohexa-1,4-dienes has been achieved by using chiral anion phase-transfer catalysis, providing a range of enantioenriched cis-3a-arylhydroindoles bearing an all-carbon quaternary stereocenter in good yields (up to 78%) and excellent enantioselectivities (up to 97% ee). Furthermore, the potential application of this methodology to natural product total synthesis was demonstrated by the asymmetric synthesis of (+)-Mesembrane.
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Efficient asymmetric syntheses of α-quaternary lactones and esters through chiral bifunctional sulfide-catalyzed desymmetrizing bromolactonization of α,α-diallyl carboxylic acids. Chem Commun (Camb) 2021; 57:10907-10910. [PMID: 34590630 DOI: 10.1039/d1cc03874e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Asymmetric halolactonizations are powerful methods for the syntheses of chiral lactones. Catalytic and highly enantioselective halolactonizations of α-allyl carboxylic acids, however, continue to present a formidable challenge. Herein, we report the chiral bifunctional sulfide-catalyzed desymmetrizing bromolactonizations of α,α-diallyl carboxylic acids. These reactions efficiently produced chiral α-quaternary lactones and esters.
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A dynamic picture of the halolactonization reaction through a combination of ab initio metadynamics and experimental investigations. Chem Sci 2021; 12:7746-7757. [PMID: 34168827 PMCID: PMC8188468 DOI: 10.1039/d1sc01014j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 04/22/2021] [Indexed: 01/23/2023] Open
Abstract
The halolactonization reaction is one of the most common electrophilic addition reactions to alkenes. The mechanism is generally viewed as a two-step pathway, which involves the formation of an ionic intermediate, in most cases a haliranium ion. Recently, an alternative concerted mechanism was proposed, in which the nucleophile of the reaction played a key role in the rate determining step by forming a pre-polarized complex with the alkene. This pathway was coined the nucleophile-assisted alkene activation (NAAA) mechanism. Metadynamics simulations on a series of model halolactonization reactions were used to obtain the full dynamic trajectory from reactant to product and investigate the explicit role of the halogen source and solvent molecules in the mechanism. The results in this work ratify the occasional preference of a concerted mechanism over the classic two-step transformation under specific reaction conditions. Nevertheless, as the stability of both the generated substrate cation and counter-anion increase, a transition towards the classic two-step mechanism was observed. NCI analyses on the transition states revealed that the activating role of the nucleophile is independent of the formation and stability of the intermediate. Additionally, the dynamic insights obtained from the metadynamics simulations and NCI analyses employed in this work, unveiled the presence of syn-directing noncovalent interactions, such as hydrogen bonding, between the alkenoic acid and the halogen source, which rationalized the experimentally observed diastereoselectivities. Explicit noncovalent interactions between the reactants and a protic solvent or basic additive are able to disrupt these syn-directing noncovalent interactions, affecting the diastereoselective outcome of the reaction.
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Catalytic enantioselective bromohydroxylation of cinnamyl alcohols. RSC Adv 2021; 11:13040-13046. [PMID: 35423889 PMCID: PMC8697332 DOI: 10.1039/d1ra02297k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 03/23/2021] [Indexed: 11/21/2022] Open
Abstract
This work describes an effective enantioselective bromohydroxylation of cinnamyl alcohols with (DHQD)2PHAL as the catalyst and H2O as the nucleophile, providing a variety of corresponding optically active bromohydrins with up to 95% ee. Optically active bromohydrins are obtained with up to 95% ee via asymmetric bromohydroxylation of cinnamyl alcohols with H2O as nucleophile.![]()
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18
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Abstract
Intermolecular asymmetric haloamination reactions are challenging due to the inherently high halenium affinity (HalA) of the nitrogen atom, which often leads to N-halogenated products as a kinetic trap. To circumvent this issue, acetonitrile, possessing a low HalA, was used as the nucleophile in the catalytic asymmetric Ritter-type chloroamidation of allyl-amides. This method is compatible with Z and E alkenes with both alkyl and aromatic substitution. Mild acidic workup reveals the 1,2-chloroamide products with enantiomeric excess greater than 95% for many examples. We also report the successful use of the sulfonamide chlorenium reagent dichloramine-T in this chlorenium-initiated catalytic asymmetric Ritter-type reaction. Facile modifications lead to chiral imidazoline, guanidine, and orthogonally protected 1,2,3 chiral tri-amines. Intermolecular haloamination reactions are challenging due to the high halenium affinity of the nitrogen atom. This is circumvented by using acetonitrile as an attenuated nucleophile, resulting in an enantioselective halo-Ritter reaction.![]()
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Catalytic Asymmetric Iodoesterification of Simple Alkenes. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202003886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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20
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Halogen-Bonding Interaction between I 2 and N-Iodosuccinimide in Lewis Base-Catalyzed Iodolactonization. Org Lett 2020; 22:4888-4892. [PMID: 32484356 DOI: 10.1021/acs.orglett.0c01735] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The halogen-bonding interaction between I2 and N-iodosuccinimide (NIS) stabilized by a Lewis base (LB) has been explored. 1H NMR, nuclear Overhauser effect (NOE), and diffusion-ordered NMR spectroscopy (DOSY) suggest the generation of a 1:1:1 assembly, LB-I2-NIS. In contrast, when N-iodotrifluoromethanesulfonimide (INTf2) is used instead of NIS, LB-I5+-LB is generated. On the basis of these results in combination with density functional theory (DFT) calculations, we propose a mechanism for the formation of I2-NIS and the subsequent generation of an active iodinating species LB-I+.
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21
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Catalytic Asymmetric Iodoesterification of Simple Alkenes. Angew Chem Int Ed Engl 2020; 59:12680-12683. [DOI: 10.1002/anie.202003886] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Indexed: 12/30/2022]
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Mechanistic Insights into the Origin of Stereoselectivity in an Asymmetric Chlorolactonization Catalyzed by (DHQD) 2PHAL. J Am Chem Soc 2020; 142:7179-7189. [PMID: 32202109 DOI: 10.1021/jacs.0c01830] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Electrophilic halofunctionalization reactions have undergone a resurgence sparked by recent discoveries in the field of catalytic asymmetric halocyclizations. To build mechanistic understanding of these asymmetric transformations, a toolbox of analytical methods has been deployed, addressing the roles of catalyst, electrophile (halenium donor), and nucleophile in determining rates and stereopreferences. The test reaction, (DHQD)2PHAL-catalyzed chlorocyclization of 4-arylpent-4-enoic acid with 1,3-dichloro-5,5-dimethylhydantoin (DCDMH), is revealed to be first order in catalyst and chlorenium ion donor and zero order in alkenoic acid substrate under synthetically relevant conditions. The simplest interpretation is that rapid substrate-catalyst binding precedes rate-limiting chlorenium attack, controlling the face selectivity of both chlorine attack and lactone closure. ROESY and DFT studies, aided by crystal structures of carboxylic acids bound by the catalyst, point to a plausible resting state of the catalyst-substrate complex predisposed for asymmetric chlorolactonization. As revealed by our earlier labeling studies, these findings suggest modes of binding in the (DHQD)2PHAL chiral pocket that explain the system's remarkable control over rate- and enantioselection-determining events. Though a comprehensive modeling analysis is beyond the scope of the present work, quantum chemical analysis of the fragments' interactions and candidate reaction paths point to a one-step concerted process, with the nucleophile playing a critical role in activating the olefin for concomitant electrophilic attack.
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23
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Natural product derivatization with β-lactones, β-lactams and epoxides toward ‘infinite’ binders. Tetrahedron 2019. [DOI: 10.1016/j.tet.2019.04.068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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24
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Association of Halogen Bonding and Hydrogen Bonding in Metal Acetate-Catalyzed Asymmetric Halolactonization. iScience 2019; 12:280-292. [PMID: 30731356 PMCID: PMC6365408 DOI: 10.1016/j.isci.2019.01.029] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 12/26/2018] [Accepted: 01/18/2019] [Indexed: 12/24/2022] Open
Abstract
Cooperative activation using halogen bonding and hydrogen bonding works in metal-catalyzed asymmetric halolactonization. The Zn3(OAc)4-3,3'-bis(aminoimino)binaphthoxide (tri-Zn) complex catalyzes both asymmetric iodolactonization and bromolactonization. Carboxylic acid substrates are converted to zinc carboxylates on the tri-Zn complex, and the N-halosuccinimide (N-bromosuccinimide [NBS] or N-iodosuccinimide [NIS]) is activated by hydrogen bonding with the diamine unit of chiral ligand. Halolactonization is significantly enhanced by the addition of catalytic I2. Density functional theory calculations revealed that a catalytic amount of I2 mediates the alkene portion of the substrates and NIS to realize highly enantioselective iodolactonization. The tri-Zn catalyst activates both sides of the carboxylic acid and alkene moiety, so that asymmetric five-membered iodolactonization of prochiral diallyl acetic acids proceeded to afford the chiral γ-butyrolactones. In the total description of the catalytic cycle, iodolactonization using the NIS-I2 complex proceeds with the regeneration of I2, which enables the catalytic use of I2. The actual iodination reagent is I2 and not NIS.
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Enantioselective Bromolactonization of Trisubstituted Olefinic Acids Catalyzed by Chiral Pyridyl Phosphoramides. Chemistry 2018; 24:18880-18885. [PMID: 30230634 DOI: 10.1002/chem.201804630] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Indexed: 11/11/2022]
Abstract
Enantioselective bromolactonization of trisubstituted olefinic acids producing synthetically useful chiral lactones with two contiguous asymmetric centers has remained mainly unexplored except for the 6-exo cyclization mode. In this work, the 5-exo- and 6-endo modes of bromocyclization of trisubstituted olefinic acids were enabled for the first time using N-bromosuccinimide and a pyridyl phosphoramide catalyst. The utility of the resulting bromolactones was demonstrated by transformations harnessing reactive alkyl bromide moieties without losing stereochemical information. Optimization studies and control experiments revealed that the basicity of pyridine moieties and presence of N-H protons in the phosphoramide species strongly affected both the reactivity and enantioselectivity parameters.
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Stereoselective aldol reactions using pseudo C 2 symmetric 1-benzyl-4-(trifluoromethyl)piperidine-2,6-dione. Chem Commun (Camb) 2018; 54:9913-9916. [PMID: 30123902 DOI: 10.1039/c8cc05458d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Crossed aldol reactions of the CF3-containing pseudo C2 symmetric cyclic imide 3 were carried out by way of the corresponding boron bisenolate to stereoselectively furnish the desired products 4 and this procedure allowed the preferential construction of the diastereomers of the compounds previously obtained from the acyclic counterpart 1.
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Recent Advances in the Organocatalytic Enantioselective Synthesis of Functionalized β-Lactones. Chem Asian J 2018; 13:2333-2349. [DOI: 10.1002/asia.201800902] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 07/20/2018] [Indexed: 01/25/2023]
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An Enantioselective Iodolactonization/Cross-Coupling Protocol for the Synthesis of Highly Substituted Enol Lactones. European J Org Chem 2018. [DOI: 10.1002/ejoc.201800642] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Enantioselective Halolactonization Reactions using BINOL-Derived Bifunctional Catalysts: Methodology, Diversification, and Applications. J Org Chem 2018; 83:5954-5968. [PMID: 29717607 PMCID: PMC5984189 DOI: 10.1021/acs.joc.8b00490] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A general protocol is described for inducing enantioselective halolactonizations of unsaturated carboxylic acids using novel bifunctional organic catalysts derived from a chiral binaphthalene scaffold. Bromo- and iodolactonization reactions of diversely substituted, unsaturated carboxylic acids proceed with high degrees of enantioselectivity, regioselectivity, and diastereoselectivity. Notably, these BINOL-derived catalysts are the first to induce the bromo- and iodolactonizations of 5-alkyl-4( Z)-olefinic acids via 5- exo mode cyclizations to give lactones in which new carbon-halogen bonds are created at a stereogenic center with high diastereo- and enantioselectivities. Iodolactonizations of 6-substituted-5( Z)-olefinic acids also occur via 6- exo cyclizations to provide δ-lactones with excellent enantioselectivities. Several notable applications of this halolactonization methodology were developed for desymmetrization, kinetic resolution, and epoxidation of Z-alkenes. The utility of these reactions is demonstrated by their application to a synthesis of precursors of the F-ring subunit of kibdelone C and to the shortest catalytic, enantioselective synthesis of (+)-disparlure reported to date.
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31
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Enantioselective Synthesis of Nelfinavir via Asymmetric Bromocyclization of Bisallylic Amide. J Org Chem 2018; 83:7290-7295. [DOI: 10.1021/acs.joc.8b00039] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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32
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Phosphine oxide-Sc(OTf)3 catalyzed enantioselective bromoaminocyclization of tri-substituted allyl N-tosylcarbamates. Sci China Chem 2018. [DOI: 10.1007/s11426-017-9192-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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33
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Abstract
The enantioselective desymmetrization of carboxylic acids by chiral Brønsted base catalysis is reported, leading to bridged bicyclic lactones with up to 94% ee. Crystallographic analysis of a substrate-catalyst complex suggests an origin of stereocontrol, reminiscent of functional Brønsted bases in biological settings, and enabled reaction optimization. The products contain an all-carbon quaternary stereocenter and can be derivatized to functionalized cyclopentanes.
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Absolute and relative facial selectivities in organocatalytic asymmetric chlorocyclization reactions. Chem Sci 2018; 9:2898-2908. [PMID: 29719676 PMCID: PMC5896375 DOI: 10.1039/c7sc04430e] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 12/24/2017] [Indexed: 12/16/2022] Open
Abstract
For four related 1,1-disubstituted olefins, (DHQD)2PHAL-catalyzed asymmetric chlorocyclization delivers Cl+ uniformly to one π face, but cyclizes with strong but differing net syn vs. anti addition.
Though (DHQD)2PHAL-catalyzed chlorocyclizations of 1,1-disubstituted olefins show useful (and in some cases, reversible) asymmetric induction, stereochemically complete descriptions of these alkene additions have remained largely unknown. Herein, based on a combination of NMR, derivative, isotope labeling, and computational studies, we present detailed stereochemical analyses of chlorocyclizations of nucleophile-tethered 1,1-disubstituted styryl systems. The selectivities of the two asymmetric bond-forming processes, namely electrophilic chlorine attack and nucleophilic ring closure, are thus mapped out independently. Under the established optimal conditions, four related chlorocyclizations were subjected to this analysis. All showed a strong preference for Cl+ delivery from the same face of the alkene. However, depending on reaction conditions and substrate identity (carboxylic acid, amide or carbamate), the internal nucleophiles may close with a strong net preference for either syn or anti addition relative to the Cl atom. Studies of both uncatalyzed and (DHQD)2PHAL-catalyzed processes place new boundary conditions on the role of the catalyst in these reactions.
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Desymmetrization of Bisallylic Amides through Catalytic Enantioselective Bromocyclization with BINAP Monoxide. Chemistry 2017; 23:16758-16762. [PMID: 29044749 DOI: 10.1002/chem.201704847] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Indexed: 01/12/2023]
Abstract
We report the first desymmetrization of bisallylic amides by enantioselective bromocyclization with BINAP monoxide as a catalyst. Depending upon the substitution pattern of the alkene moieties, densely functionalized, optically active oxazoline or dihydrooxazine compounds were obtained in a highly stereoselective manner. The remaining alkene moiety was subjected to various functional group manipulations to afford a diverse array of chiral molecules with multiple stereogenic centers.
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Diastereoselective Mannich reactions of pseudo- C2-symmetric glutarimide with activated imines. Beilstein J Org Chem 2017; 13:2473-2477. [PMID: 29234474 PMCID: PMC5704755 DOI: 10.3762/bjoc.13.244] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 11/09/2017] [Indexed: 11/23/2022] Open
Abstract
As an extension of the boron enolate-based aldol reactions, the oxazolidinone-installed bisimide 1a from 3-(trifluoromethyl)glutaric acid was employed for Mannich reactions with tosylated imines 2 as electrophiles to successfully obtain the corresponding adducts in a stereoselective manner.
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Abstract
γ-Butenolides, γ-butyrolactones, and derivatives, especially in enantiomerically pure form, constitute the structural core of numerous natural products which display an impressive range of biological activities which are important for the development of novel physiological and therapeutic agents. Furthermore, optically active γ-butenolides and γ-butyrolactones serve also as a prominent class of chiral building blocks for the synthesis of diverse biological active compounds and complex molecules. Taking into account the varying biological activity profiles and wide-ranging structural diversity of the optically active γ-butenolide or γ-butyrolactone structure, the development of asymmetric synthetic strategies for assembling such challenging scaffolds has attracted major attention from synthetic chemists in the past decade. This review offers an overview of the different enantioselective synthesis of γ-butenolides and γ-butyrolactones which employ catalytic amounts of metal complexes or organocatalysts, with emphasis focused on the mechanistic issues that account for the observed stereocontrol of the representative reactions, as well as practical applications and synthetic potentials.
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Cinchona Alkaloid Derived Primary Amine Catalyzed Intramolecular Desymmetrizing Aldolization Reaction of Diacetonyloxindoles. European J Org Chem 2017. [DOI: 10.1002/ejoc.201700155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Catalytic enantioselective bromohydroxylation of aryl olefins with flexible functionalities. Org Chem Front 2017. [DOI: 10.1039/c6qo00636a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A highly enantioselective bromohydroxylation of aryl olefins with flexible functionalities has been achieved with (DHQD)2PHAL as a catalyst and H2O as a nucleophile, giving a variety of optically active bromohydrins with up to 98% ee.
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Cinchona-Alkaloids Based Isoselenazolones: Synthesis and Their Catalytic Reactivity in Asymmetric Bromolactonization of Alkenoic Acid. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES INDIA SECTION A-PHYSICAL SCIENCES 2016. [DOI: 10.1007/s40010-016-0306-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Monomeric Cinchona Alkaloid-Based Catalysts for Highly Enantioselective Bromolactonisation of Alkynes. Chemistry 2016; 22:18601-18607. [DOI: 10.1002/chem.201604003] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Indexed: 01/14/2023]
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Regioselective organocatalyzed asymmetric bromolactonization of aryl acrylate-type carboxylic acids: a new approach towards enantioenriched 3-substituted isobenzofuranones. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.tetasy.2016.07.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Rhodium-Catalyzed Asymmetric Cycloisomerization and Parallel Kinetic Resolution of Racemic Oxabicycles. Angew Chem Int Ed Engl 2016; 55:10074-8. [DOI: 10.1002/anie.201604937] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Indexed: 12/12/2022]
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Rhodium-Catalyzed Asymmetric Cycloisomerization and Parallel Kinetic Resolution of Racemic Oxabicycles. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201604937] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Catalytic Enantioselective Desymmetrization Reactions to All-Carbon Quaternary Stereocenters. Chem Rev 2016; 116:7330-96. [DOI: 10.1021/acs.chemrev.6b00094] [Citation(s) in RCA: 468] [Impact Index Per Article: 58.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Phosphine Oxide-Sc(OTf)3 Catalyzed Highly Regio- and Enantioselective Bromoaminocyclization of (E)-Cinnamyl Tosylcarbamates. An Approach to a Class of Synthetically Versatile Functionalized Molecules. Org Lett 2016; 18:896-9. [PMID: 26894481 DOI: 10.1021/acs.orglett.5b03459] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A highly regio- and enantioselective bromoaminocyclization of (E)-cinnamyl tosylcarbamates catalyzed by a chiral phosphine oxide-Sc(OTf)3 complex is described. A wide variety of optically active aryl 5-bromo-1,3-oxazinan-2-ones can be obtained with high yield and enantioselectivity.
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Highly Enantioselective Bromocyclization of Allylic Amides with a P/P=O Double-Site Lewis Base Catalyst. Chemistry 2016; 22:2127-2133. [DOI: 10.1002/chem.201503153] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Indexed: 01/10/2023]
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A convenient method for the synthesis of α-carboxylate ester bromolactones via bromolactonization of alkenoic diesters. Org Biomol Chem 2016; 14:3202-6. [DOI: 10.1039/c6ob00311g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A simple and efficient synthesis of α-ester bromolactones has been developed through the electrophilic bromocyclization of olefinic 1,3-diesters.
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