Stereoseletive Reduction of β-Hydroxy Ketones to 1,3-Diols with the Aid of a Terphenylboronic Acid

Abstract
1-Hydroxy-6,8-diphenyl-1,2,3,4-tetrahydro-2-oxa-1-boranaphthalene (terphenylboronic acid 1), is employed for stereoselective reduction of acyclic and cyclic β-hydroxy ketones. The terphenylboronic acid 1 and acyclic β-hydroxy ketones 2 are converted to the corresponding boronates by azeotropic removal of water. The resulting boronates are treated in situ with reducing reagents to give syn 1,3-diols 3 almost exclusively. Anti α-substituted β-hydroxy ketones 8 are also reduced to give anti, anti 1,3-diol 9 stereoselectively. Furthermore, the reduction of 3-hydroxy-1-cyclopentanone gives a cis diol 11 in high selectivity.