O-Protecting groups as long-range stereocontrolling elements in the addition of acetylides to 4-substituted quinolines

Abstract

Addition of magnesium acetylides in the presence of chloroformate esters to racemic differently O-protected 2-(4-quinolyl)propanols and to enantiopure 2-(4-quinolyl)-1,3-dialkoxypropanes, prepared by a chemoenzymatic route, gives almost exclusive regioselective attack at C-2, with stereoselectivities from moderate to good, depending mainly on the bulkiness of the O-protecting group present.