It has been shown that trialkylvinylborate can react with electrophiles such as iodine,l epoxide,2 and aldehyde in a similar manner to trialkylalkynylborate.3 Recently, we have carried out the carboxylation of trialkylalkynylborate yielding a stereospecific a,P-unsaturated acid in high yield.4 Here, we report the result of the reaction between trialkylvinylborate and carbon dioxide. Under pressure, chloromagnesium trialkylvinylborate re-
