Reaction of 4-methoxy-4-(1-methylethenyl)-2-cyclobutenone derivatives with 2-lithiopropene and α-lithiostyrene: synthesis of eight-membered ring carbocycles

2-Alkyl- or phenyl-substituted 4-methoxy-4-(1-methylethenyl)-2-cyclobutenones react with 2-lithiopropene or α-lithiostyrene to produce 4-methoxy-2,4-cyclooctadienones in moderate yield, accompanied by varying amounts of 4-methoxy-4-(1-methylethenyl)-2-cyclohexenones. The reaction is general for 2-alkyl substituted 4-methoxy-4-(1-methylethenyl)-2-cyclobutenones.