O2 -Assisted Four-Component Reaction of Vinyl Magnesium Bromide with Chiral N-tert-Butanesulfinyl Imines To Form syn-1,3-Amino Alcohols.

An O2 -assisted, four-component reaction has been developed to synthesize a wide range of syn-1,3-amino alcohols in one step. The reaction proceeds by oxygenation of vinyl magnesium bromide (component-I) with O2 (component-II) to give a magnesium enolate of acetaldehyde, which undergoes addition to a chiral N-tert-butanesulfinyl imine (component-III) followed by a sequential addition with excess vinyl magnesium bromide (component-IV). The approach allows diastereoselective synthesis of anti/syn- and syn/syn-3-amino-1,5-diols in good yields with high diastereoselectivity. The method was illustrated in an efficient, four-step synthesis of piperidine alkaloid (-)-2'-epi-ethylnorlobelol.