Allylboronates react with beta -ketoacids to yield tertiary homoallylic beta -hydroxycarbsxylic acids. The reaction presumably proceeds via a bicyclic transition state. The beta -carboxylic substituent enhances the rate of the reaction.
Barluenga, Jose; Florez, Josefa; Yus, Miguel, Journal of the Chemical Society. Perkin transactions I, 1983, # 12, p. 3019 - 3026