A concise and divergent approach to radicamine B and hyacinthacine A3 based on a step-economic transformation

Recent advances in the total synthesis of polyhydroxylated alkaloids via chiral oxazines

This review summarizes recently established methodologies developed for the enantioselective and diastereoselective synthesis of chiral 1,3-oxazines. These compounds are of interest as advanced synthetic intermediates in the total synthesis of structurally complex and biologically active polyhydroxylated alkaloids such as (+)-1-deoxynojirimycin, (-)-anisomycin, (+)-castanospermine, (+)-casuarine, (-)-conduramine F-1, (-)-sphingofungin B, Neu5Ac methyl ester, and other natural products. The devised synthetic approach aims to offer a direct, efficient, and adaptable method for obtaining both pure enantiomers and pure diastereomers. It revolves around utilizing chiral building blocks like syn,syn-, syn,syn,anti-, syn,anti-, syn,anti,syn-, anti,syn-, anti,syn,syn-, and anti,syn,anti-oxazines. By integrating oxazine chemistry with established and innovative transformations, this approach enabled the synthesis of 30 polyhydroxylated amines across various studies conducted between 2007 and 2022.

Synthesis of di- and trihydroxy proline derivatives from D-glycals: Application in the synthesis of polysubstituted pyrrolizidines and bioactive 1C-aryl/alkyl pyrrolidines

Six different types of O-benzyl protected proline derivatives have been synthesized from D-glycals and 2C-formyl-glycals. One of the di-O-benzyl protected proline derivatives has been utilized for the synthesis of polysubstituted pyrrolizidines via [3 + 2] cycloaddition in a stereoselective manner. Further, we also report on the stereoselective synthesis of biologically active 1C-aryl/alkyl pyrrolidines i.e. 4-epi-radicamine B, 4-epi-radicamine A, 1C-butyl and 1C-methyl pyrrolidines through double reductive amination of a variety of D-glucal derived diketones with p-methoxybenzylamine.

Amide activation: an emerging tool for chemoselective synthesis

It is textbook knowledge that carboxamides benefit from increased stabilisation of the electrophilic carbonyl carbon when compared to other carbonyl and carboxyl derivatives. This results in a considerably reduced reactivity towards nucleophiles. Accordingly, a perception has been developed of amides as significantly less useful functional handles than their ester and acid chloride counterparts. However, a significant body of research on the selective activation of amides to achieve powerful transformations under mild conditions has emerged over the past decades. This review article aims at placing electrophilic amide activation in both a historical context and in that of natural product synthesis, highlighting the synthetic applications and the potential of this approach.

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.

Pyrrolizidine alkaloids

This review covers pyrrolizidine alkaloids isolated from natural sources. Topics include: aspects of structure, isolation, and biological/pharmacological studies; total syntheses of necic acids, necine bases and closely-related non-natural analogues.