CHIRALITY CONTROL BY THE AID OF 2,2-DIMETHYLOXAZOLIDINE CHIRAL AUXILIARIES - HIGHLY 1,4-CHIRAL INDUCTIVE ASYMMETRIC ALKYLATIONS OF AMIDE ENOLATES

The propanamide and methoxyacetamide derivatives of (S)-4-benzyl-2,2,5 ,5-tetramethyioxazolidine, a new chirality controlling auxiliary based on the restricted rotation around amide bond, generate chiral lithium Z-enolates by lithiation. They undergo highly lk-1,4- and ul-1,4-indu ctive alkylations with a variety of alkylating reagents, respectively. The diastereotopic face participated in the reactions is that remote from the 4-shielding substituent of oxazolidine in the syn-conformatio ns. Coplanarity between the enolate double bond and the oxazolidine pl ane in the transition state can be a major factor for the observed exc ellent selectivities.