HIGHLY SELECTIVE RING-CLEAVAGE OF ACETALS CATALYZED BY PHENYLBORON COMPLEXES DERIVED FROM SULFONAMIDES OF ALPHA-AMINO-ACIDS

In the presence of catalytic amount (0.1-0.5 equiv) of phenylboron com plex 5d and nucleophiles 4a-e (1.5-1.1 equiv), chiral cyclic acetals ( 2S,4R)-3a-d undergo efficient ring-cleavage reaction to give 7a-h with high stereoselectivity. Removal of the chiral auxiliary from the ring -cleavage products 7a-h by a two step sequence furnishes functionalize d secondary alcohols 8a-h of high enantiomeric purities.