N-sulfinyl β-amino Weinreb amides:: Synthesis of enantiopure β-amino carbonyl compounds.: Asymmetric synthesis of (+)-sedridine and (-)-allosedridine

N-Sulfinyl beta-amino Weinreb amides are prepared by condensation of sulfinimines with the potassium enolate of N-methoxy-N-methylacetamide. These new chiral building blocks are useful for the asymmetric synthesis of beta-amino carbonyl compounds, as illustrated here by the concise enantioselective syntheses of sedum alkaloids (+)-sedridine and (-)-allosedridine.