Stereodivergent Synthesis of Pseudotabersonine Alkaloids

Stereocontrolled Construction of Acyclic Quaternary Carbon Centers via α-Hydroxymethylation of α-Branched N-tert-Butanesulfinyl Ketimines

Hydroxymethylation of α-branched N-tert-butanesulfinyl ketimines with formaldehyde equivalents was developed to stereoselectively construct acyclic quaternary stereocenters bearing two sterically and electronically similar substituents. The stereoselective tBuOK-promoted α-deprotonation of acyclic ketimines allowed for the stereodefined formation of fully substituted aza-enolates, followed by facially selective C-C bond formation involving formaldehyde formed in situ, yielding α-hydroxymethylated products with precise stereocontrol.

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.

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.

Divergent synthesis of polysubstituted cyclopropanes and β-silyoxy imidates via switchable additions of N-tert-butanesulfinylimidates to acylsilanes

A switchable addition of N-tert-butanesulfinylimidates to acylsilanes leads to divergent synthesis of polysubstituted cyclopropanes and β-silyloxy imidates.