REGIOCHEMISTRY OF THE REARRANGEMENT OF CYCLOHEXENYL AND CYCLOHEXADIENYL PHOSPHATES TO BETA-KETO PHOSPHONATES

Diethyl vinyl phosphates derived from substituted cyclohexanones are known to rearrange to tf-keto phosphonates upon treatment with excess LDA. To develop strategies for the regiocontrol of this rearrangement, the effect of regiospecific preparation of the vinyl phosphate has been tested and the use of dienyl phosphates has been studied. With 3-methylcyclohexanone both phosphonate regioisomers are formed in a ratio independent of the regiochemistry of the vinyl phosphate. However, regiocontrol is observed in rearrangements of dienyl phosphates derived from methyl-substituted cyclohexenones. In this series, formation of the kinetic enolate, reaction with diethyl phosphorochloridate, and in situ treatment of the intermediate vinyl phosphate with LDA result in the phosphono ketone, with C-P bond formation at the site corresponding to the original kinetic enolate. Catalytic hydrogenation of the phosphono enone then can be used to obtain a phosphono ketone. In contrast to the course of this rearrangement with cyclohexenones, the diethyl vinyl phosphate derivative of cycloheptenone undergoes a 1,2-rearrangement yielding a hydroxy phosphonate. © 1990, American Chemical Society. All rights reserved.