Catalytic enantioselective α-tosyloxylation of ketones using iodoaryloxazoline catalysts: insights on the stereoinduction process.

A family of iodooxazoline catalysts was developed to promote the iodine(III)-mediated α-tosyloxylation of ketone derivatives. The α-tosyloxy ketones produced are polyvalent chiral synthons. Through this study, we have unearthed a unique mode of stereoinduction from the chiral oxazoline moiety, where the stereogenic center alpha to the oxazoline oxygen atom is significant. Computational chemistry was used to rationalize the stereoinduction process. The catalysts presented promote currently among the best levels of activity and selectivity for this transformation. Evaluation of the scope of the reaction is presented.

Resolution of 2,2-disubstituted epoxides via biocatalytic azidolysis.

A practical procedure for the enzymatic resolution of 2-alkyl-2-aryl-disubstituted epoxides using the Codex HHDH P2E2 enzyme and sodium azide is reported. This method allowed the synthesis of novel regio- and enantioselective 1-azido-2-arylpropan-2-ols in excellent yields. Furthermore, these intermediates were used for the preparation of enantiomerically enriched amino alcohols and aziridines containing a tertiary center.

Stereocontrolled synthesis of C1-C17 fragment of narasin via a free radical-based approach.

An efficient synthesis of the C1-C17 western unit of narasin was achieved from (S)-Roche ester. Highlights in our synthesis include the successful exploitation of three stereoselective sequences of Lewis acid mediated reaction followed by free-radical-based hydrogen transfer.