L. D. Buyck, R. Verhé, N. Kimpe
Jan 18, 1983
Citations
0
Influential Citations
9
Citations
Journal
Bulletin des Sociétés Chimiques Belges
Abstract
2, 3, 5, 6-Tetrachloro-4,4-dimethyl-2,5-cyclohexadienone (4), a useful precursor for synthetic filicinic acid (5). was prepared in 88-94% yield by poly-chlorination of 4,4-dimethyl-2-cyclohexenone (1) or 4,4-dimethylcyclohexanone (11) with chlorine in dimethylformamide under dehydrochlorinating conditions. Introduction of the fourth chlorine atom required a medium saturated with hydrogen chloride and an optimal temperature in the range of 40-70°C. This is in accord with chlorination of the enol resulting from Michael addition of hydrogen chloride to the trichlorodienone 3, followed by dehydrochlorination. Besides the one-pot procedure for 4, stepwise methods provided several intermediates in high yields.