A versatile synthesis, including asymmetric synthesis, of bicyclo[ n.1.0]alkanes from cyclic ketones via the magnesium carbenoid 1,3-CH insertion as a key reaction

Abstract

Treatment of 1-chlorovinyl p-tolyl sulfoxides, which were synthesized from various cyclic ketones and chloromethyl p-tolyl sulfoxide in three steps, in high yields, with lithium enolate of tert-butyl acetate or its homologues gave the adducts in quantitative yields. The adducts were treated with isopropylmagnesium chloride in ether in dry toluene as the reaction solvent to afford bicyclo[ n.1.0]alkanes in high to quantitative yields via magnesium carbenoid 1,3-CH insertion. When this method was carried out starting from unsymmetrical cyclic ketones and ( R)-chloromethyl p-tolyl sulfoxide, an asymmetric synthesis of bicyclo[ n.1.0]alkane was realized.