Lithium Methylborohydride. A New Stereoselective Reducing Agent for Reduction of Cyclic Ketones

Abstract

Although in the past decade considerable efforts have been devoted to the development of the hindered trialkylborohydrides which allow conversion of cyclic and bicyclic ketones into the thermodynamically less stable alcohols in excellent stereoselectivity,¹ there are few reports in the literature on the use of monoalkylborohydride reducing agents.² As part of our research program directed toward the development of new hydride reducing agents, we have recently reported the reducing properties of lithium n-butylborohydride.³ This paper describes useful synthetic potential of lithium methylborohydride for highly stereoselective reductions of cyclic ketones.