Esters of β-ketophosphonic acids - Communication 8. Reaction of 2,6-dibromocyclohexanone with triethyl phosphite

Abstract

1. The reaction of triethyl phosphite with 2,6-dibromocyclohexanone follows a complex course. In addition to the expected diethylphosphoric ester of the enol form of the ester of cyclohexanone-2-phosphonic-1 acid, by-products are formed which are produced by conversions of the latter compound (diethyl ester of cyclohexanone-2-phosphonic-1 acid and tetraethyl ester of hypophosphoric acid), and also an intermediate product, diethyl bromo-6-cyclohexen-1-yl phosphoric ester [diethylcyclohexadien-1,5-yl phosphate, diethyl phenyl phosphate]. 2. The cis- and trans-isomers of 2,6-dibromocyclohexanone react differently with triethyl phosphite. The trans-isomer gives the diethylphosphoric ester of the enol form of the ester of cyclohexanone-2-phosphonic-1 acid as the main reaction product. With the cis-form the diethyl ester of cyclohexanone-2-phosphonic-1 acid is formed. In both cases, the products enumerated in paragraph 1 also are obtained. © 1962 Consultants Bureau Enterprises, Inc.