An O 2 -assisted, four-component reaction has been developed to synthesizeawide range of syn-1,3-amino alcohols in one step.T he reaction proceeds by oxygenation of vinyl magnesium bromide (component-I) with O 2 (component-II) to give am agnesium enolate of acetaldehyde,w hich undergoes addition to ac hiral N-tert-butanesulfinyl imine (component-III) followed by asequential addition with excess vinyl magnesium bromide (component-IV). The approach allows diastereoselective synthesis of anti/syn-and syn/syn-3amino-1,5-diols in good yields with high diastereoselectivity. The method was illustrated in an efficient, four-step synthesis of piperidine alkaloid (À)-2'-epi-ethylnorlobelol.

An O 2 -assisted, four-component reaction has been developed to synthesizeawide range of syn-1,3-amino alcohols in one step.T he reaction proceeds by oxygenation of vinyl magnesium bromide (component-I) with O 2 (component-II) to give am agnesium enolate of acetaldehyde,w hich undergoes addition to ac hiral N-tert-butanesulfinyl imine (component-III) followed by asequential addition with excess vinyl magnesium bromide (component-IV). The approach allows diastereoselective synthesis of anti/syn-and syn/syn-3amino-1,5-diols in good yields with high diastereoselectivity. The method was illustrated in an efficient, four-step synthesis of piperidine alkaloid (À)-2'-epi-ethylnorlobelol.