文摘
The reduction of (5S)-2-amino-5-dibenzylamino-4-oxo-1,6-diphenylhex-2-ene was optimized for diastereoselectivity andoverall conversion to (2S,3S,5S)-5-amino-2-dibenzylamino-3-hydroxy-1,6-diphenylhexane (2a). A two-step reduction sequence is described wherein the enamine is reduced with aborane-sulfonate derivative followed by reduction of the resulting ketone with sodium borohydride. The desired 2a wasobtained with 84% diastereoselectivity and an acyclic 1,4stereoinduction ratio of 14:1. This methodology has been usedto produce multikilogram quantities of the diamino alcohol coreof Ritonavir and should be general to the synthesis of relateddiamino hydroxyethylene isosteres.