ON THE STEREOSELECTIVITY OF THE (-)-DIMENTHYL MALONATE ADDITION TO ALPHA,BETA-UNSATURATED KETONES

The Michael addition of (-)-dimenthyl malonate to eight alpha, beta-un saturated ketones has been studied. The ratio of diastereomers was cal culated on the basis of the H-1 NMR spectra of the crude reaction prod ucts. The diastereomer excess Varied from 10 to 50%, depending on the structure of the starting enone. The pure diastereomer produced by add ition of (-)-dimenthyl malonate to 2-benzylidene-1,4-indandione was is olated by repeated crystallization. X-ray analysis has shown that the isomer is (-)-dimenthyl 2-[1-(1,3-dioxoindan-2-yl)-1-phenylmethyl]malo nate (5a). The predominating diastereomers of -dimenthyl(3-ferrocenyl- 3-oxophenylpropyl)malonate (1a) and -(1,3-dioxo[3]ferrocenophan-2-yl)- 1-phenylmalonate (6a) were also isolated in pure state by careful crys tallization.