CamTHP*OH: A Camphor-Derived δ-Lactol Auxiliary for the Effective Desymmetrization of Attached Glycinamide Residues. Asymmetric Synthesis of α-Amino Carbonyl Compounds

Stereoselective allylation of camphor and subsequent terminal hydroformylation affords a new δ-lactol auxiliary (camTHP*OH) 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 α-amino amide products which may be converted directly to α-amino ketones on treatment with Grignard or organolithium reagents without loss of stereochemical integrity.