Hydrochloric Acid → hexahydro-3-(3-oxocyclohexen-1-yl)-2H-azepin-2-one

Participants

Reaction Steps

Lithium diisopropylamide, prepared by treating diisopropylamine (45.3 ml) with 1.4 M butyl lithium in hexane (231 ml) at -10° C. under nitrogen, was treated at -60° C. with 1-trimethylsilylhexahydro-2H-azepin-2-one (63.7 g) in dry THF (50 ml). The white suspension was treated after 20 minutes with a solution of 3-methoxy-2-cyclohexenone (40.8 g) in THF (50 ml). The resulting solution was allowed to warm to ambient temperature. After a further 3 hours the cooled solution was treated with concentrated hydrochloric acid (120 ml) and stirred for 18 hours. The THF layer was combined with several chloroform extracts from the aqueous layer. Evaporation of the solvent gave a yellow solid, which was recrystallised from ethyl acetate to give hexahydro 3-(3-oxocyclohexen-1-yl) -2H-azepin-2-one as an off-white solid (45.5 g) m.p. 159°-165° C.

Provenance & Evidence