three-step sequence. Monochlorination of 3 was carried out in methylene chloride with an equimolar amount of chlorine. The reaction was monitored via NMR and upon appearance of a singlet at 2.3 ppm the reaction was quenched. Traces of starting material and the dichloro ketone were removed by spinning-band distillation. Preparation of the bromo chloro ketone was accomplished by treating the monochloro ketone with N-bromosuccinimide in ...
