European Journal of Organic Chemistry
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The generation of a new Lewis acid (BF2OBn·OEt2) has been reported, and its usefulness has been demonstrated in the regio- and stereoselective ring-opening of trisubstituted epoxides. This Lewis acid is one in a series of new Lewis acids generated from BF3·OEt2 that display varying levels of Lewis acidity. When paired with a modified Shi epoxidation protocol, highly functionalized propionate units, such as those found in a wide variety of natural products, can be accessed. In conjunction with a Mukaiyama oxidative cyclization employing our second generation catalyst Co(nmp)2, this procedure ultimately culminated in the shortest and highest yielding route towards the methyl-substituted trans-tetrahydrofuran (trans-THF) fragment present in amphidinolide C, C2, and F.