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Highly Enantioselective Brønsted Acid Catalyzed Heyns Rearrangement
Jin Cao1, Yu-Xuan Su1, Xin-Yu Zhang1
1Frontiers Science Center for New Organic Matters, State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, 300071, Tianjin, China.
Abstract:
Herein we report the first method for highly enantioselective Brønsted acid catalyzed Heyns rearrangements. These reactions, catalyzed by a chiral spiro phosphoric acid, afforded synthetically valuable chiral α-aryl-α-aminoketones which cannot be obtained by means of previously reported Heyns rearrangement methods. This method features low catalyst loadings, high yields and high enantioselectivities, making these reactions highly practical. We used the method to efficiently synthesize various chiral amines, including some biologically active molecules. We experimentally proved that these acid-catalyzed Heyns rearrangements proceeded via a proton-transfer process involving an enol intermediate and the stereocontrol was realized during the proton-transfer step.
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