Addition of 2-[(trimethylsilyloxy)]furan to 2-acetyl-1,4-benzoquinone using chiral non-racemic copper(II)-pybox catalysts

The Michael addition of 2-[(trimethylsilyloxy)]furan 1 to 2-acetyl-1,4-benzoquinone 2 was carried out using several Cu(II)-pybox catalysts.The furobenzofuran adduct 3 was prepared in good chemical yield but in low enantiomeric excess.The adduct 3 was converted into the menthyl carbonate derivative to allow determination of the enantiomeric excess by high field NMR spectroscopy.