ja049323b_si_001.cif (19.67 kB)

Enantioselective and Structure-Selective Diels−Alder Reactions of Unsymmetrical Quinones Catalyzed by a Chiral Oxazaborolidinium Cation. Predictive Selection Rules

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posted on 21.04.2004, 00:00 by Do Hyun Ryu, Gang Zhou, E. J. Corey
The chiral oxazaborolidinium cation 1 promotes Diels−Alder reactions between 2-triisopropylsilyloxy-1,3-butadiene and a number of unsymmetrical 1,4-benzoquinones in a highly enantioselective and structurally selective manner. The basis for the enantioselectivity is explained rationally in terms of a preferred type of transition-state assembly. Selection rules have been developed that allow the prediction of the principal reaction product of Diels−Alder reaction between unsymmetrical diene and quinone components.