BF2OBn·OEt2: A Lewis Acid, Its Use in a Regio‐ and Stereoselective Opening of Trisubstituted Epoxides, and Its Application towards Amphidinolide C and F. Issue 4 (10th December 2012)

• Record Type: Journal Article
• Authors: Morra, Nicholas A.; Pagenkopf, Brian L.
• Is Part Of: European journal of organic chemistry. Issue 4(2013)
• Page Start: 756
• Page End: 760
• Publication Date: 2012-12-10
• Subjects: Natural products -- Asymmetric catalysis -- Regioselectivity -- Cyclization -- Lewis acids -- Epoxidation; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.201201331
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: The generation of a new Lewis acid (BF2 OBn· 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. Abstract : The new Lewis acid BF2 OBn· OEt2 was generated by an anionic redistribution between BF3 · OEt2 and benzyloxytrimethylsilane and used in a regio‐ and stereoselective epoxide ring‐opening reaction. The utility of this reaction was demonstrated by the conversion of commercially available 2, 3‐dihydrofuran into the C‐1–C‐9 fragment of amphidinolide C and F in five steps and 49 % overall yield.