An approach to the synthesis of the cytotoxic natural product auripyrone A 1 via the cyclization of an alcohol onto a γ-pyrone in 3 is described. The bis(pyrone) alcohol 3 was prepared efficiently from the advanced aldolate 4 via silyl ether cleavage, oxidation, pyrone formation, and PMB ether removal. Instead of providing auripyrone A 1, the attempted cyclization of 3 gave the product of 1,5-acyl migration 8. Model studies show this to be a general process; therefore, cyclization of an alcohol on such a hindered γ-pyrone under normal conditions is very difficult.Treatment of the bis(pyrone) alcohol 3 with an acid did not give the desired cytotoxic product, auripyrone A, 1, but rather an acyl transfer to give 8. Model studies show this to be a general process and therefore such a cyclization is very difficult.
