Favorskii reaction of 2-bromobicyclo(3.3.1)nonan-3-one.

Abstract

Both 2β-bromobicyclo[3.3.1]nonan-3-one (IIa) and its 2α- epimer (IIb) afforded methyl bicyclo[3.2.1]octane-6β-carboxylate (IIIa) stereoselectively in the Favorskii reaction using sodium methoxide in methanol. In the reaction using sodium methoxide in dimethoxyethane (DME) at room temperature, the stereoselectivity decreased and the product was contaminated with methyl bicyclo[3.2.1]octane-6α-carboxylate (IIIb). However, when the reaction in DME was carried out at 0°C, IIIa was the only product.The routes involved in these transformations were examined by using nuclear magnetic resonance spectroscopic techniques with the deuterated compounds.