HALOGENATED KETENES .32. CYCLO-ADDITION OF DICHLOROKETENE WITH SILYL ENOL ETHERS

The generation of dichloroketene by the zinc dechlorination of trichloroacetyl chloride in the presence of silyl enol ethers results in good yields of 2, 2-dichloro-3-siloxycyclobutanones. The silyl substituent is easily removed to yield the 3-hydroxycyclobutanones. Several of the siloxycyclobutanones and 3-hydroxycyclobutanones were thermally unstable and underwent a silicon migration and ring-opening reaction to yield l, l-dichloro-2, 4-diones. This thermal instability is related to conformational effects in the cyclobutanone ring. The chlorine atoms on the 2, 2-dichloro-3-siloxycyclobutanones are readily removed by tri-n-butyltin hydride reduction. © 1979, American Chemical Society. All rights reserved.