Asymmetric synthesis of epohelmins A, B and 3-epi ent-epohelmin A

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

The synthesis of nitrogen-containing heterocycles, including natural alkaloids and other compounds presenting different types of biological activities have proved to be successful employing chiral sulfinyl imines derived from tert-butanesulfinamide. These imines are versatile chiral auxiliaries and have been extensively used as eletrophiles in a wide range of reactions. The electron-withdrawing sulfinyl group facilitates the nucleophilic addition of organometallic compounds to the iminic carbon with high diastereoisomeric excess and the free amines obtained after an easy removal of the tert-butanesulfinyl group can be transformed into enantioenriched nitrogen-containing heterocycles. The goal of this review is to the highlight enantioselective syntheses of heterocycles involving the use of chiral N-tert-butanesulfinyl imines as reaction intermediates, including the synthesis of several natural products. The synthesis of nitrogen-containing heterocycles in which the nitrogen atom is not provided by the chiral imine will not be considered in this review. The sections are organized according to the size of the heterocycles. The present work will comprehensively cover the most pertinent contributions to this research area from 2012 to 2020. We regret in advance that some contributions are excluded in order to maintain a concise format.

Catalytic, Enantioselective Formal Synthesis of Monoterpene Indole Alkaloid (-)-Alstoscholarine

A catalytic, enantioselective formal synthesis of monoterpene indole alkaloid (-)-alstoscholarine is described. The synthesis employs an Ir-amine dual catalyzed asymmetric allylation of aldehyde 8 with 3-indolyl vinyl carbinol derivative 7 to furnish chiral aldehyde 6 as a key asymmetric step. Other key reactions include the construction of the 2-ketopyrrole moiety by Nicolaou's method and Tf₂O promoted Pictet-Spengler cyclization to access Zhu's intermediate 3.

A practical approach to asymmetric synthesis of dolastatin 10

Dolastatin 10, an antineoplastic agent for cancer chemotherapy, is a linear peptide possessing N,N-dimethyl Val-OH, l-valine, (3R,4S,5S)-dolaisoleucine, (2R,3R,4S)-dolaproine and (S)-dolaphenine. Our efficient synthesis includes the following three key features: (1) SmI₂-induced cross-coupling was employed to couple aldehyde 11 with (S)-N-tert-butanesulfinyl imine 12 to generate the required stereocenters of Dap (7); (2) asymmetric addition of chiral N-sulfinyl imine 10 provided a straightforward approach to the synthesis of the protected Doe ((S,S)-8); (3) a practical method to the key subunit Val-Dil (24a) has been established as an alternative synthetic route for the synthesis of this challenging chemical structure.

Recent advances on the total synthesis of alkaloids in mainland China

Alkaloids are a large family of natural products that mostly contain basic nitrogen atoms. Because of their intriguing structures and important functions, they have long been popular targets for synthetic organic chemists. China's chemists have made significant progress in the area of alkaloid synthesis over past decades. In this article, selected total syntheses of alkaloids from research groups in mainland China during the period 2011–16 are highlighted.

An efficient approach to trans-4-hydroxy-5-substituted 2-pyrrolidinones through a stereoselective tandem Barbier process: divergent syntheses of (3R,4S)-statines, (+)-preussin and (−)-hapalosin

Natural products of (+)-preussin and (−)-hapalosin have been asymmetrically synthesized through the stereoselective tandem Barbier process.