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Influence of Pore Size in Benzoin Condensation of Furfural Using Heterogenized Benzimidazole Organocatalysts. Chemistry 2022; 28:e202202771. [PMID: 36302695 PMCID: PMC10108080 DOI: 10.1002/chem.202202771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 10/24/2022] [Accepted: 10/24/2022] [Indexed: 11/06/2022]
Abstract
A designed N-heterocyclic carbene (NHC) catalyst was covalently anchored on a range of mesoporous and hierarchical supports, to study the influence of pore size in the benzoin condensation of furfural. The structural and spectroscopic characteristics of the anchored catalysts were investigated, also with the help of molecular dynamics simulations, in order to rationalize the degree of stability and recyclability of the heterogenized organocatalysts. Quantitative yields (99 %) and complete recyclability were maintained after several cycles, vindicating the design rationale.
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Studying the reactivity of alkyl substituted BODIPYs: first enantioselective addition of BODIPY to MBH carbonates. Chem Sci 2021; 12:4503-4508. [PMID: 34163715 PMCID: PMC8179495 DOI: 10.1039/d0sc06574a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/03/2021] [Indexed: 12/27/2022] Open
Abstract
The first enantioselective addition of alkyl BODIPYs to Morita-Baylis-Hillman (MBH) carbonates is reported. This is the first reported enantioselective methodology using the methylene position of BODIPYs as a nucleophile. The reaction is efficiently catalyzed by cinchona alkaloids, achieving high enantioselectivities and total diastereoselectivity. The use of cinchona alkaloid pseudo enantiomers (chinine/cinchonine) allows us to obtain both pairs of enantiomers in similar yields and enantioselectivities, a common issue in this type of reaction. The photophysical study of these dyes (absorption and fluorescence) has been performed in order to determine their parameters and explore future possible application in bioimaging. In addition, electronic circular dichroism (ECD) studies supported by time-dependent density functional theory (TD-DFT) calculations were also performed.
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Highly Regio‐ and Enantioselective Organocatalytic γ‐Allylic Alkylation of Quinolines. Adv Synth Catal 2021. [DOI: 10.1002/adsc.202001213] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Synthesis, Photophysics, and Solvatochromic Studies of an Aggregated-Induced-Emission Luminogen Useful in Bioimaging. SENSORS (BASEL, SWITZERLAND) 2019; 19:E4932. [PMID: 31726748 PMCID: PMC6891498 DOI: 10.3390/s19224932] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 11/06/2019] [Accepted: 11/07/2019] [Indexed: 12/29/2022]
Abstract
Biological samples are a complex and heterogeneous matrix where different macromolecules with different physicochemical parameters cohabit in reduced spaces. The introduction of fluorophores into these samples, such as in the interior of cells, can produce changes in the fluorescence emission properties of these dyes, caused by the specific physicochemical properties of cells. This effect can be especially intense with solvatofluorochromic dyes, where changes in the polarity environment surrounding the dye can drastically change the fluorescence emission. In this article, we studied the photophysical behavior of a new dye and confirmed the aggregation-induced emission (AIE) phenomenon with different approaches, such as by using different solvent proportions, increasing the viscosity, forming micelles, and adding bovine serum albumin (BSA), through analysis of the absorption and steady-state and time-resolved fluorescence. Our results show the preferences of the dye for nonpolar media, exhibiting AIE under specific conditions through immobilization. Additionally, this approach offers the possibility of easily determining the critical micelle concentration (CMC). Finally, we studied the rate of spontaneous incorporation of the dye into cells by fluorescence lifetime imaging and observed the intracellular pattern produced by the AIE. Interestingly, different intracellular compartments present strong differences in fluorescence intensity and fluorescence lifetime. We used this difference to isolate different intracellular regions to selectively study these regions. Interestingly, the fluorescence lifetime shows a strong difference in different intracellular compartments, facilitating selective isolation for a detailed study of specific organelles.
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Hybrid catalysts based on N-heterocyclic carbene anchored on hierarchical zeolites. RSC Adv 2019; 9:35336-35344. [PMID: 35528109 PMCID: PMC9074450 DOI: 10.1039/c9ra07516j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 10/18/2019] [Indexed: 01/30/2023] Open
Abstract
Hybrid materials have been synthesized by anchoring a N-heterocyclic carbene (NHC) precursor on different inorganic zeolitic supports with hierarchical porosity, in particular hierarchical HZSM-5 and SAPO-5. Hierarchical porous inorganic supports have been obtained both by top-down and bottom-up approaches and the role of hierarchical porosity has been evaluated. A detailed physico-chemical characterization has been performed on the organic–inorganic hybrids using a multi-technique approach (XRD, volumetric and thermogravimetric analysis, ssNMR and FTIR) in order to establish a structure–property relationship. The hybrids were tested in the benzoin condensation reaction of furfural, a base catalyzed reaction. N-heterocyclic carbene has been grafted on hierarchical HZSM-5 and SAPO-5 to obtain hybrid catalysts, that are active in the benzoin condensation reaction.![]()
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Synergistic Catalysis: Highly Enantioselective Cascade Reaction for the Synthesis of Dihydroacridines. Chemistry 2019; 25:7623-7627. [PMID: 30964218 DOI: 10.1002/chem.201901498] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Indexed: 11/10/2022]
Abstract
The first stereoselective synthesis of dihydroacridines through synergistic catalysis, achieving the final target compounds with good to excellent yields and good to excellent enantioselectivities and diastereoselectivities, is reported. The synergistic approach consists in the activation of substituted quinolines with a Lewis acid catalyst that react in a cascade fashion with activated enals in the iminium form. Mechanistic calculations support a consecutive Michael-aldol reaction, followed by dehydration.
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Proline bulky substituents consecutively act as steric hindrances and directing groups in a Michael/Conia-ene cascade reaction under synergistic catalysis. Chem Sci 2019; 10:4107-4115. [PMID: 31015949 PMCID: PMC6457335 DOI: 10.1039/c8sc05258a] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 03/03/2019] [Indexed: 12/23/2022] Open
Abstract
In this study, we report a highly stereoselective and versatile synthesis of spiro pyrazolones, promising motifs that are being employed as pharmacophores.
In this study, we report a highly stereoselective and versatile synthesis of spiro pyrazolones, promising motifs that are being employed as pharmacophores. The new synthetic strategy merges organocatalysis and metal catalysis to create a synergistic catalysis using proline derivatives and Pd catalysts. This protocol is suitable for late-stage functionalization, which is very important in drug discovery. Additionally, a thorough computational study proved to be very useful to elucidate the function of the different catalysts along the reaction, showing a peculiar feature: the –CPh2OSiMe3 group of the proline catalyst switches its role during the reaction. In the initial Michael reaction, this group plays its commonly-assumed role of bulky blocking group, but the same group generates π–Pd interactions and acts as a directing group in the subsequent Pd-catalyzed Conia-ene reaction. This finding might be very relevant especially for processes with many steps, such as cascade reactions, in which functional groups are assumed to play the same role during all reaction steps.
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Correction: Synergistic formal ring contraction for the enantioselective synthesis of spiropyrazolones. Chem Sci 2019. [DOI: 10.1039/c9sc90160d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Correction for ‘Synergistic formal ring contraction for the enantioselective synthesis of spiropyrazolones’ by Marta Meazza et al., Chem. Sci., 2018, 9, 6368–6373.
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Acid properties of organosiliceous hybrid materials based on pendant (fluoro)aryl-sulfonic groups through a spectroscopic study with probe molecules. Catal Sci Technol 2019. [DOI: 10.1039/c9cy01609k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hybrid heterogeneous catalysts containing (fluoro)aryl-sulfonic groups were characterized through combined spectroscopic techniques and adsorption of probe molecules, with their reactivity being modulated for acetal formation.
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12
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Organocatalytic Formation of Chiral Trisubstituted Allenes and Chiral Furan Derivatives. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201806238] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Organocatalytic Formation of Chiral Trisubstituted Allenes and Chiral Furan Derivatives. Angew Chem Int Ed Engl 2018; 57:10661-10665. [DOI: 10.1002/anie.201806238] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 06/15/2018] [Indexed: 01/17/2023]
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Synergistic Catalysis: Highly Enantioselective Acetyl Aza-arene Addition to Enals. Chemistry 2018; 24:13306-13310. [PMID: 29989264 DOI: 10.1002/chem.201802303] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 06/21/2018] [Indexed: 01/08/2023]
Abstract
A novel catalytic enantioselective methodology based on synergistic catalysis for the synthesis of chiral 2-acyl pyridines and pyrazines is reported. The strategy involves the metal-Lewis acid activation of acetyl aza-arenes and the secondary-amine activation of enals. The proposed mechanism is supported by DFT calculations.
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Synergistic formal ring contraction for the enantioselective synthesis of spiropyrazolones. Chem Sci 2018; 9:6368-6373. [PMID: 30310564 PMCID: PMC6115638 DOI: 10.1039/c8sc00913a] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 06/28/2018] [Indexed: 01/10/2023] Open
Abstract
We report the first ring contraction/formal [6 + 2] cycloaddition using synergistic Pd(0)/secondary amine catalysis, obtaining [5,5]-spiropyrazolone derivatives in excellent yields and stereoselectivities. We detected the key palladium activated intermediate in its protonated form by mass spectrometry and characterized its structure by infrared spectroscopy and DFT calculations, allowing us to propose a conceivable mechanistic pathway for this reaction.
The rapid generation of molecular complexity from simple reactants is a key challenge in organic synthesis. Spiro compounds, underrepresented 3D motifs in chemical libraries, represent a challenge due to the creation of spiro quaternary carbon and the need to control the 3D shape in one step. Herein, we report the first ring contraction/formal [6 + 2] cycloaddition using synergistic Pd(0)/secondary amine catalysis, obtaining [5,5]-spiropyrazolone derivatives in excellent yields and stereoselectivities. We demonstrate that this reaction has a broad scope of early and late stage derivatization that will benefit the creation of highly valuable chemical libraries using spiropyrazolone motifs. We detected the key palladium activated intermediate in its protonated form by mass spectrometry and characterized its structure by infrared spectroscopy and DFT calculations, allowing us to propose a conceivable mechanistic pathway for this reaction.
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Abstract
Vinyl cyclopropanes are amongst the most useful building blocks in organic synthesis. Their easy opening and capacity to generate dipoles have been exploited for the synthesis of cyclopentanes with good yields and sometimes excellent stereoselectivities. In this review we give an overview of their applications, focusing on the present century.
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Abstract
In this review we summarize the latest developments in the enantioselective synthesis of spirocompounds. The most important organometallic and organocatalytic methodologies are highlighted.
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Synergistic catalysis: enantioselective cyclopropanation of alkylidene benzoxazoles by Pd(ii) and secondary amine catalysis. Scope, limitations and mechanistic insight. Org Chem Front 2018. [DOI: 10.1039/c7qo00858a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An enantioselective synergistic cascade cyclopropanation/NHC catalyzed ring opening has been reported. DFT calculations have been performed to confirm the mechanism.
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Indium(III)-catalyzed Aza-Conia-Ene Reaction for the Synthesis of Indolizines. Chemistry 2017; 23:7905-7909. [PMID: 28444826 DOI: 10.1002/chem.201701820] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Indexed: 01/03/2023]
Abstract
A new indium(III)-catalyzed reaction for the synthesis of a series of indolizine scaffolds has been developed. This methodology was highly efficient, allowing a low catalyst loading of 2 mol % (down to 0.5 mol %) and rendering the products in high yields through a 5-exo-dig aza-Conia-ene reaction. Furthermore, the possibility of incorporating an electrophile into the generated pyrrolidone ring in a one-pot synergistic fashion was demonstrated. Finally, based on experimental observations, a mechanism proposal was outlined.
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Highly Diastereo- and Enantioselective Synthesis of α-Spiro-δ-lactams by an Organocascade Reaction. European J Org Chem 2017. [DOI: 10.1002/ejoc.201700193] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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21
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Highly Enantioselective Synthesis of Alkylpyridine Derivatives through a Michael/Michael/Aldol Cascade Reaction. European J Org Chem 2017. [DOI: 10.1002/ejoc.201601491] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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22
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Synergistic Diastereo- and Enantioselective Functionalization of Unactivated Alkyl Quinolines with α,β-Unsaturated Aldehydes. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611306] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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23
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Synergistic Catalysis: Asymmetric Synthesis of Cyclopentanes Bearing Four Stereogenic Centers. SYNTHESIS-STUTTGART 2016. [DOI: 10.1055/s-0036-1588347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Synergistic Catalysis for the Asymmetric [3+2] Cycloaddition of Vinyl Aziridines with α,β-Unsaturated Aldehydes. Chemistry 2016; 23:268-272. [DOI: 10.1002/chem.201604995] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Indexed: 11/08/2022]
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Decarboxylative [4+2] Cycloaddition by Synergistic Palladium and Organocatalysis. Angew Chem Int Ed Engl 2016; 55:15272-15276. [PMID: 27897423 DOI: 10.1002/anie.201607788] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Indexed: 01/16/2023]
Abstract
A novel reaction based on synergistic catalysis, combining palladium- and organocatalysis has been developed. The palladium catalyst activates vinyl benzoxazinanones via a decarboxylation to undergo a [4+2] cycloaddition with iminium-ion activated α,β-unsaturated aldehydes. The reaction is demonstrated to proceed for a number of combinations of vinyl benzoxazinanones reacting with α,β-unsaturated aldehydes, providing highly substituted vinyl tetrahydroquinolines in good to high yields, and excellent enantio- and diastereoselectivities (>98 % ee and >20:1 d.r.). The palladium catalyst used in the synergistic catalysis can be re-used in a one-pot sequential coupling reaction with an aromatic boronic acid forming the coupling product in 95 % yield, >20:1 d.r. and 99 % ee.
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Decarboxylative [4+2] Cycloaddition by Synergistic Palladium and Organocatalysis. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201607788] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Synergistic Catalysis: Enantioselective Ring Expansion of Vinyl Cyclopropanes Combining Four Catalytic Cycles for the Synthesis of Highly Substituted Spirocyclopentanes Bearing up to Four Stereocenters. Chemistry 2016; 22:9923-8. [PMID: 27198468 DOI: 10.1002/chem.201601893] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Indexed: 01/01/2023]
Abstract
A double synergistic cascade reaction is reported, combining transition metal and amine catalysis. The reaction between vinyl cyclopropanes and enals renders the final cyclopentane derivatives in excellent yields and stereoselectivities.
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Enantioselective Organocatalytic Cyclopropanation of Enals Using Benzyl Chlorides. J Org Chem 2016; 81:3488-500. [DOI: 10.1021/acs.joc.5b02801] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Synergistic catalysis: cis-cyclopropanation of benzoxazoles. Chem Sci 2016; 7:984-988. [PMID: 29081942 PMCID: PMC5633913 DOI: 10.1039/c5sc03597j] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 10/30/2015] [Indexed: 11/25/2022] Open
Abstract
In the present paper we report our latest efforts in pushing the boundaries of synergistic catalysis. We propose the use of 3 different catalytic cycles working in concert for the formation of cis cyclopropane derivatives of benzoxazoles with excellent stereoselectivities. This is the proof of concept that synergistic catalysis could be successfully used in cascade reactions.
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Organocatalytic Fluoromalonate Addition to Tetrahydroisoquinolines through a CDC process. ChemistrySelect 2016. [DOI: 10.1002/slct.201500022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Expanding the scope of Metal-Free enantioselective allylic substitutions: Anthrones. Sci Rep 2015; 5:16886. [PMID: 26592555 PMCID: PMC4655356 DOI: 10.1038/srep16886] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 10/19/2015] [Indexed: 11/09/2022] Open
Abstract
The highly enantioselective asymmetric allylic alkylation of Morita–Baylis–Hillman carbonates with anthrones is presented. The reaction is simply catalyzed by cinchona alkaloid derivatives affording the final alkylated products in good yields and excellent enantioselectivities.
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Synergistic catalysis: highly diastereoselective benzoxazole addition to Morita-Baylis-Hillman carbonates. Chem Commun (Camb) 2015; 50:7447-50. [PMID: 24875953 DOI: 10.1039/c4cc00728j] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An expedited method has been developed for the diastereoselective synthesis of highly functionalized alkyl-azaarene systems with good yields and high diastereoselectivities (>15 : 1 dr). The methodology includes a synergistic catalysis event involving organometallic (10 mol% AgOAc) activation of an alkyl azaarene and Lewis base (10 mol% DABCO) activation of a Morita-Baylis-Hillman carbonate. The structure and relative configuration of a representative product were confirmed by X-ray analysis.
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Synergistic catalysis: enantioselective addition of alkylbenzoxazoles to enals. Chemistry 2014; 20:16853-7. [PMID: 25352171 DOI: 10.1002/chem.201404565] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Indexed: 01/25/2023]
Abstract
A novel catalytic enantioselective methodology based on synergistic catalysis is reported. The strategy involves: 1) the metal-Lewis-acid activation of alkylazaarenes, and 2) the secondary-amine activation of enals. Consequently, highly functionalized chiral alkylazaarenes were obtained in good yields and with reasonable stereoselectivity.
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