Asymmetric Synthesis of Acyclic 1,3-Amino Alcohols by Reduction of N-Sulfinyl β-Amino Ketones. Formal Synthesis of (-)-Pinidinol and (+)-Epipinidinol

Stereoselective reduction of acyclic N-sulfinyl beta-amino ketones with (LiEt3BH) and Li(t-BuO)(3)AlH, respectively, gave anti- and syn-1,3-amino alcohols with excellent selectivity. A formal asymmetric synthesis of the hydroxy piperidine alkaloids (-)-pinidinol and (+)-epipinidinol from a common N-sulfinyl beta-amino ketone ketal precursor was developed. The pinidinol piperidine ring was formed via a novel acid-catalyzed cascade reaction of a N-sulfinylamino silyl protected alcohol ketal.