N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

Diastereoselective Addition of Lithiated Allenyl Sulfones to Nonracemic Sulfinimines: Asymmetric Synthesis of Diverse Heterocycles

The addition of lithiated allenyl sulfones to nonracemic sulfinimines furnished sulfinamides possessing the allenyl sulfonyl moiety with excellent diastereoselectivity. The formed products are transformed into different heterocycles, including the synthesis of pyrroline, pyran, and functionalized benzopyran.

A Disconnection for Rapid Access to Heterocyclic Benzylic Amines with Fully Substituted α-Carbons

2- or 4-Pyridyl benzylic amines represent a privileged motif in drug discovery. However, the formation of heterocyclic benzylic amines with fully substituted α-carbons can require the execution of lengthy synthetic routes, which limit their application. Addition of various nucleophilic agents to Ellman's imines has been well established; however, there is no precedented literature reported for pyridyl-type nucleophiles, which are very important for medicinal chemistry. In this letter, we disclose the development of a one-step synthesis of heterocyclic benzylic amines with fully substituted α-carbons from heteroaryl halides and sulfinyl imines. Starting from 2,4-dibromopyridine, regioselective synthesis of 2- or 4-pyridyl benzylic amines could be achieved by choosing toluene or MTBE as a solvent.

Cyclic Sulfinamides

The literature on cyclic sulfinamides (put simply, sultims) published from 1989 to 2022 has been summarized and reviewed. The information is divided into two sections: the analysis of synthetic methods on the preparation of cyclic sulfinamides and the discussion of the chemical properties of cyclic sulfinamides focusing on their reactions and applications. The survey of the reaction conditions, provided in the most detailed way, and a critical view of the reaction mechanisms add an extra dimension to the text. The data presented will be useful to specialists in different areas, especially those who work in the field of synthetic organic and pharmaceutical chemistry.

Stereoselective Synthesis of Densely Substituted Pyrrolidines via a [3 + 2] Cycloaddition Reaction between Chiral N-tert-Butanesulfinylazadienes and Azomethine Ylides

The N-tert-butanesulfinylimine group behaves as a suitable electron-withdrawing group in 1-azadienes, allowing the diastereoselective synthesis of densely substituted pyrrolidines by 1,3-dipolar cycloadditions (1,3-DCs) with azomethylene ylides. The use of Ag2CO3 as catalyst has allowed one to obtain a wide variety of proline derivatives with high regio- and diastereoselectivities. Subsequent efficient transformations provide valuable proline derivatives, some of which can be used as organocatalysts. The influence of the N-tert-butanesulfinyl group on the diastereoselectivity was studied by computational methods.

Catalytic enantioselective reductive alkynylation of amides enables one-pot syntheses of pyrrolidine, piperidine and indolizidine alkaloids

The primary objective in synthetic organic chemistry is to develop highly efficient, selective, and versatile synthetic methodologies, which are essential for discovering new drug candidates and agrochemicals. In this study, we present a unified strategy for a one-pot, catalytic enantioselective synthesis of α-alkyl and α,α'-dialkyl pyrrolidine, piperidine, and indolizidine alkaloids using readily available amides and alkynes. This synthesis is enabled by the identification and development of an Ir/Cu/N-PINAP catalyzed highly enantioselective and chemoselective reductive alkynylation of α-unbranched aliphatic amides, which serves as the key reaction. This reaction is combined with Pd-catalyzed tandem reactions in a one-pot approach, enabling the collective, catalytic enantioselective total syntheses of eight alkaloids and an anticancer antipode with 90-98% ee. The methodology's enantio-divergence is exemplified by the one-step access to either enantiomer of alkaloid bgugaine.

Stereoselective Synthesis of α-Disubstituted β-Homoprolines

An efficient enantioselective synthesis of chiral α-disubstituted β-homoprolines was developed, starting with the stereodivergent allylation of chiral N-tert-butanesulfinyl imines derived from 4-bromobutanal with indium or zinc and using well-established and reliable synthetic transformations. This methodology allows the easy introduction of different substituents at the α-position of the pyrrolidine scaffold and is characterized by the possibility of switching the absolute configuration of the newly formed stereocenter either by changing the configuration of the tert-butanesufinamide chiral auxiliary or by using a different stereodivergent allylation protocol with the same auxiliary.

Desymmetrization of Cyclohexadienones through Phase-Transfer-Catalyzed Stereoselective Intramolecular Aza-Michael Addition with Chiral Sulfinamide Nucleophiles

This paper reports the desymmetrization of cyclohexadienones through stereoselective intramolecular aza-Michael addition with a tethered chiral sulfinamide nucleophile. The reaction was facilitated by phase-transfer catalysis and produced various nitrogen-containing bicyclic compounds with a yield of up to 93% and a diastereomeric ratio of up to >20:1.

Lithio Tris(methylthio)methane as Hydroxy/Thio/Aminocarbonyl Anion Equivalent: Asymmetric Synthesis of α-Amino Acid Esters, Thioesters, Amides, and Peptides

The use of lithio tris(methylthio)methane as a hydroxy/thio/amino carbonyl anion equivalent in the synthesis of α-amino acids is reported. Addition of the reagent to nonracemic sulfinimines furnished the α-sulfinamido trithioformates in excellent diastereoselectivity. Unmasking the trithioformates to diverse functionalities, such as α-amino acid thioesters, esters, anilides, amides, and di/tri peptides, without epimerization of chiral centers was accomplished.

Piperidine Derivatives: Recent Advances in Synthesis and Pharmacological Applications

Piperidines are among the most important synthetic fragments for designing drugs and play a significant role in the pharmaceutical industry. Their derivatives are present in more than twenty classes of pharmaceuticals, as well as alkaloids. The current review summarizes recent scientific literature on intra- and intermolecular reactions leading to the formation of various piperidine derivatives: substituted piperidines, spiropiperidines, condensed piperidines, and piperidinones. Moreover, the pharmaceutical applications of synthetic and natural piperidines were covered, as well as the latest scientific advances in the discovery and biological evaluation of potential drugs containing piperidine moiety. This review is designed to help both novice researchers taking their first steps in this field and experienced scientists looking for suitable substrates for the synthesis of biologically active piperidines.

Ten-Step Total Synthesis of (-)-Andranginine

The total synthesis of the indole alkaloid (-)-andranginine has been achieved in 10 steps. Key reactions of the synthesis include a nucleophilic addition of acetylenyl anion to chiral N-sulfinyl imine, an intramolecular N-alkylation reaction to close the C ring, and a dienyne metathesis cascade reaction to construct the DE rings. Meanwhile, 16-epi-(-)-andranginine was also obtained with the developed strategy.

Diastereoselective Hydroxylation of N-tert-Butanesulfinyl Imines with 2-(Phenylsulfonyl)-3-phenyloxaziridine (Davis Oxaziridine)

The diastereoselective α-hydroxylation of N-tert-butanesulfinyl metallodienenamine and metalloenamines with Davis oxaziridine affords α-hydroxy N-sulfinyl imines with 50-88% yield and up to 98:2 diastereomeric ratio. Dramatic changes in diastereoselectivity and stereoselectivity were observed by choice of metal bases. The mechanistic understanding for the switch in diastereoselectivity was assisted by DFT computational modeling, which suggests the facial approach is governed by aza-enolate geometry. A one-pot protocol for the asymmetric synthesis of 1,2-amino alcohols is described.

Synthetic Approach toward Enantiopure Cyclic Sulfinamides

A synthetic approach toward densely substituted enantiopure cyclic sulfinamides possessing up to four consecutive stereogenic centers was developed based on a completely diastereoselective S_N2′ cyclization/tert-Bu cleavage sequence. Diastereospecific transformation of the obtained scaffold into chiral S^VI derivatives such as sulfoximines and sulfonimidamides is demonstrated.

Dichotomous Selectivity in Indium-Mediated Aza-Barbier-Type Allylation of 2-N-Acetyl Glycosyl Sulfinylimines in Brine: Convenient Access to Potent Anti-Influenza Agents

A highly diastereoselective indium-mediated allylation of 2-N-acetyl glycosyl sulfinylimines in brine under mild reaction conditions is reported. The method allows the achievement of a highly remarkable dichotomous selectivity for substrates, providing a single diastereoisomer of the product in 80-98% yield. With chiral (S)-homoallylic sulfinamide (R_S)-5 and (R_S)-8 formed as key intermediates, two potent anti-influenza agents, zanamivir and zanaphosphor, were synthesized in 50% and 41% overall yields, respectively.

Synthesis of Isothiazoles through N-Propargylsulfinylamide: TFA-Promoted Sulfinyl Group-Involved Intramolecular Cyclization

A new reactivity mode of tert-butanesulfinamide has been developed, which proceeds through C-S and O-S bond cleavage of N-propargyl tert-butanesulfinylamide allowing rapid assembly of poly functionalized isothiazoles. This intramolecular cyclization reaction could be conducted under mild and convenient conditions and tolerates several fluoroalkyl and substituted phenyl groups with good chemical yields. This reaction not only represents a new reactivity of tert-butanesulfinamide but also provides an easy strategy for the synthesis of isothiazoles.