CamTHP*OH: a camphor-derived delta-lactol auxiliary for the effective desymmetrization of attached glycinamide residues. Asymmetric synthesis of alpha-amino carbonyl compounds.

Stereoselective allylation of camphor and subsequent terminal hydroformylation affords a new delta-lactol auxiliary (camTHPOH) on multigram scale. Stereoselective condensation with glycine dimethylamide and Cbz protection affords a camTHP-desymmetrized glycinamide building block which undergoes efficient and highly diastereoselective metal enolate alkylation reactions. Acid-mediated deprotection affords the N-Cbz-protected alpha-amino amide products which may be converted directly to alpha-amino ketones on treatment with Grignard or organolithium reagents without loss of stereochemical integrity. [reaction: see text]