cis -Selective synthesis of 2,5-disubstituted pyrrolidines

Ruthenium catalyzed synthesis of enaminones

The Grubbs first-generation catalyst has been found to be an effective catalyst for the synthesis of enaminones by coupling thioamides with α-diazodicarbonyl compounds. The reaction is successful in converting primary, secondary, and tertiary thioamides into their corresponding enaminones. The reaction is also suitable for the synthesis of chiral enaminones.

2,5-Disubstituted pyrrolidines: synthesis by enamine reduction and subsequent regioselective and diastereoselective alkylations

Methodology for the diastereoselective synthesis of 2,5-disubstituted pyrrolidines by reduction of enamines derived from pyroglutamic acid is reported; the nature of nitrogen protection was found to be critical for the stereochemical control of the reaction outcome. Regioselective manipulation of the C-2 and C-5 substituents is possible, providing access to differently substituted pyrrolidines for a limited number of cases.

Unexpected epimerization at C2in the Horner–Wadsworth–Emmons reaction of chiral 2-substituted-4-oxopiperidines

The observed epimerization at C2 in the Horner-Wadsworth-Emmons (HWE) reaction of chiral 2-substituted-4-oxopiperidines has been investigated and, on the basis of the experimental results, a mechanism for this unexpected process has been proposed.

trans-2,5-Disubstituted pyrrolidines: rapid stereocontrolled access from sulfones

A direct and versatile route for the reliable synthesis of trans-2,5-disubstituted pyrrolidines from pyroglutamic acid is reported, which can be conducted at scale and without chromatographic purification of key intermediates.