W. Baik et al., CHEMOSELECTIVE REACTIONS OF ANTHRONE WITH ALPHA,BETA-UNSATURATED KETONES, Journal of chemical research. Synopses (Print), (7), 1998, pp. 358
In the presence of ZnCl2, 1,4-conjugated addition of anthrone with alp
ha,beta-unsaturated ketones proceeded to give mono-Michael adducts, wh
ereas in basic solution it gave bis-Michael adducts.