The totalsynthesis of pteridicacids A and B is reported. The convergent asymmetric synthesis involved the use of a diastereoselective ethyl ketone aldol reaction followed by an efficient spiroketalization and provided pteridicacids A and B in 2.9% and 2.8% overall yield, respectively.
A convergent approach to the totalsynthesis of pteridicacid A, having potent plant growth regulator activity, is described. Key steps include the desymmetrization of bicyclic olefin with Brown’s chiral hydroboration, acid-mediated spiroketalization, and zirconium-catalyzed ethylmagnesation protocol to install the ethyl stereocenter at C14.