A convergent stereoselective total synthesis of racemic phthoxazolin A

[GRAPHICS] The first total synthesis of phthoxazolin A is reported which involves a convergent series of palladium-catalyzed cross coupling reactions to stereoselectively construct the Z,Z,E-trienyl unit of phthoxazolin A. The most important steps of the synthesis involve using vinylboronate pinacol ester as a vinyl dianion equivalent, by employing a Heck coupling of a vinyl iodide with the vinylboronate, followed by a deboronation-iodination sequence with inversion of alkene stereochemistry and Stille coupling of the resulting vinyl iodide.