4-SUBSTITUTED-5,5-DIMETHYL OXAZOLIDIN-2-ONES AS EFFECTIVE CHIRAL AUXILIARIES FOR ENOLATE ALKYLATIONS AND MICHAEL ADDITIONS

4-(Methyl, phenyl, benzyl, and i-propyl)-5,5-dimethyl-oxazolidin-2-ones, readily available from α-amino acids, are shown to be effective chiral auxiliaries for stereoselective enolate alkylations and conjugate additions of attached N-acyl moieties. © 1995

One-pot nitro-Mannich/hydroamination cascades for the direct synthesis of 2,5-disubstituted pyrroles using base and gold catalysis.

An efficient, easy to perform, one-pot reaction cascade for the synthesis of 2,5-disubstituted pyrroles from p-toluenesulfonyl protected imines and 4-nitrobut-1-yne under a combination of base and gold(III) catalysis is reported

SYNTHESIS OF 5-SUBSTITUTED-3,3-DIMETHYL-2-PYRROLIDINONES - QUAT CHIRAL AUXILIARIES

The synthesis of a series of chiral auxiliaries, 5-substituted-3,3-dimethyl-2-pyrrolidinones, "quats", from L-glutamic acid is described. Efficient regeneration of the chiral auxiliaries from their N-pivaloyl derivatives is readily achieved with LiOH in THF-water at 20°C. © 1994

SYNTHESIS OF 5-SUBSTITUTED-3,3-DIMETHYL-2-PYRROLIDINONES - QUAT CHIRAL AUXILIARIES

The synthesis of a series of chiral auxiliaries, 5-substituted-3,3-dimethyl-2-pyrrolidinones, "quats", from L-glutamic acid is described. Efficient regeneration of the chiral auxiliaries from their N-pivaloyl derivatives is readily achieved with LiOH in THF-water at 20°C. © 1994

ASYMMETRIC ALDOL AND ALKYLATION REACTIONS MEDIATED BY THE QUAT CHIRAL AUXILIARY (R)-(-)-5-METHYL-3,3-DIMETHYL-2-PYRROLIDINONE

Enolates derived from the N-propionoyl derivative of the "quat" chiral auxiliary (R)-(-)-5-methyl-3,3-dimethyl-2-pyrrolidinone undergo highly stereoselective aldol and alkylation reactions. Removal of the auxiliary has been demonstrated with LiOH, PhCH2OLi, MeOMgBr and LiAlH4 to generate respectively (2R,3R)-3-hydroxy-2-methyl-3-phenylpropionic acid in homochiral form, and with 96% e.e. (S)-2-methyl-3-phenylpropionic acid and derived methyl and benzyl esters and with >94% e.e. (S)-2-methyl-3-phenylpropanol. © 1994

Oxidative functionalisation of SuperQuat enamides: Asymmetric synthesis of homochiral 1,2 diols

Homochiral (E)-enamides derived from (S)-4-phenyl-5,5-dimethyl-oxazolidin-2-one undergo highly diastereoselective epoxidation upon treatment with dimethyldioxirane (DMDO). Treatment with m-chloroperbenzoic acid (MCPBA) produces syn-(4S, 1′R,2′)-1′ -acyloxy-2′-hydroxy derivatives with high diastereoselectivity, consistent with a mechanism involving initial epoxidation and subsequent in situ S N1 type epoxide opening and trapping with m-chlorobenzoic acid. Reductive cleavage of the isolated 1′-acyloxy-2′-hydroxy derivatives generates 1,2-diols in high yields and in high ee