Short, enantioselective total synthesis of aflatoxin B2 using an asymmetric [3+2]-cycloaddition step.

Gang Zhou, E J Corey

Index: J. Am. Chem. Soc. 127(34) , 11958-9, (2005)

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Abstract

A highly enantioselective [3+2]-cycloaddition reaction of 2,3-dihydrofuran with 1,4-benzoquinones using a chiral oxazaborolidinium triflimidate as catalyst has been developed which allows rapid access to a variety of chiral phenolic tricycles (enantiomeric excesses ranging from 91 to 98%). The utility of this new methodology is demonstrated by a short synthesis of the important pentacyclic natural product, aflatoxin B2. This exploratory study indicates that an even broader application of these catalysts to enantioselective cycloadditions may be possible.