N-Sulfinyl β-Amino Weinreb Amides: Synthesis of Enantiopure β-Amino Carbonyl Compounds. Asymmetric Synthesis of (+)-Sedridine and (−)-Allosedridine

[reaction: see text] 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.