Malonate Anion Induced Favorskii-Type Rearrangement. Reaction of Cyclic α-Halo Ketones with Sodiomalonates

Article abstract of DOI:10.1021/jo01289a011

The reaction of 2-chlorocyclohexanone (1b) with ethyl sodiomalonate in benzene at 0-25 deg C gave 6-bicyclo<3.1.0>hexan-6-ol (4c), the Favorskii-type intermediate, in 49percent yield, in place of the substitution product ethyl C-(2-oxocyclohexyl)malonate (3).Derivatives of bicyclo<4.1.0>heptan-7-ol (4a,b) and those of bicyclo<3.1.0>hexan-6-ol (4d,e) were also obtained in good yields by similar means.Compound 4c was transformed into 3 readily by heating with 0.05 equiv of NaH in benzene.The hydrolysis of 4a-d with 0.2 N NaOH followed by pyrolysis at 110-120 deg C gave the ring-contracted β-keto esters 9a-d.Pyrolysis after the hydrolysis with 2N NaOH gave the corresponding ketones 11a-d in good yields.Oxidation of 4c with CrO3 and HClO4 afforded ethyl C-(2-hydroxycyclopentanecarbonyl)malonate (14) in 45 percent yield.Treatment of 4c with Br2 gave ethyl C-(1-bromocyclopentanecarbonyl)malonate (18) in 64 percent yield.