Control of five contiguous stereogenic centers in an organocatalytic kinetic resolution via michael/acetalization sequence: Synthesis of fully substituted tetrahydropyranols

An organocatalytic kinetic resolution of racemic secondary nitroallylic alcohols via Michael/acetalization sequence to give fully substituted tetrahydropyranols is described. The process affords the products with high to excellent stereoselectivities (up to 19.9:1.5:1 dr and 98% ee). The highly enantioenriched, less reactive (S)-nitroallylic alcohols 3 were isolated with good to high chemical yields (30-44%). The synthetic application of the resolved substrate is shown toward the synthesis of enantioenriched (+)-(2S,3R)-3-amino-2-hydroxy-4-phenylbutyric acid.