Scheme 5. 1,4-ACA of Grignard reagents to cyclic dienone S10 catalysed by CuBr-1b complex. aConversions were monitored by TLC. bRatios between 1,4 : 1,6-adducts were determined by 1H NMR spectroscopy analysis on the crude mixture. cIsolated yields after silica gel chromatography. dee were determined by chiral-phase GC analysis.
