Phenolic Oxidative Coupling with Hypervalent Iodine. A Synthesis of 6a-Epipretazettine

Article abstract of DOI:10.1021/jo00161a038

6a-Epipretazettine was synthesized in seven steps from piperonal and synephrine.Intramolecular, monophenolic, oxidative coupling of a functionalized benzylic acetal, employing benzene as oxidant, gave a spirodienone in 13 percent yield.Subsequent deprotection of the secondary amine was followed by spontaneous closure to a tetracyclic pyrrolidine possessing an all-cis ring fusion.This substance was reduced with diisobutylaluminum hydride, and the resulting alcohol was transformed, via methanolysis of the corresponding mesylate, to O-methyl-6a-epipretazettine.Acidic hydrolysis of the latter yielded 6a-epipretazettine, identical with material previously obtained by Danishefsky.