Abstract: The mild reducing agent tetramethylammonium triacetoxyborohydride reduces acyclic P-hydroxy ketones to their corresponding anti diols with high diastereoselectivity. a- Alkyl substitution does not significantly affect the stereoselectivity of these reductions. In all cases examined, good to excellent yields of diastereomerically homogeneous diols were obtained. The mechanism of these reductions involves an acid-promoted ligand exchange ...