Unusual reagent control of diastereoselectivity in the 1,2-addition of hard carbon nucleophiles to C-6-heteroatom substituted cyclohexenones
by Lindsay, Harriet A.; Salisbury, Catherine L.; Cordes, Wally; McIntosh, Matthias C.
[GRAPHICS] A surprising and synthetically useful counterion-dependent reversal of diastereoselectivity was found in 1,2-additions of hard carbon nucleophiles to C-6-heterosubstituted cyclohexenones. In general, Grignard reagents added syn to the C-6-substituent and Li reagents added anti, although some exceptions were found. Selectivities could be increased in some cases by appropriate choice of solvent and/or cosolvent.