Addition of a chiral non-racemic silyloxypyrrole to an activated 1,4-benzoquinone

Abstract

The uncatalyzed addition of enantiopure silyloxypyrrole 3 to 2-carbomethoxy-1,4-benzoquinone 4 in acetonitrile at ambient temperature afforded pyrrolidinonobenzofuran adducts 5 and 6 in low yield. The two adducts were separated by flash chromatography and the structures of these diastereomers were determined using high field NMR spectroscopy combined with molecular modelling studies. The work reported herein provides the first example of the annulation of a 1,4-benzoquinone with a chiral non-racemic silyloxypyrrole.