Additive-free oxychlorination of unsaturated C-C bonds with -butyl hypochlorite and water.

Herein we report an additive-free protocol for the facile synthesis of α,α-dichloroketones and α-chlorohydrins from various aryl terminal, diaryl internal, and aliphatic terminal alkynes and alkenes, respectively. The commercially available -butyl hypochlorite (BuOCl) was employed as a suitable chlorinating reagent, being accompanied by the less harmful BuOH as the by-product. In addition, the oxygen atoms in the products came from water rather than molecular oxygen, based on the O-labelling experiments. Meanwhile, the diastereoselectivity of the - and the corresponding -alkenes has been compared and rationalized. Using a group of control experiments, the possible mechanisms have been proposed as the initial electrophilic chlorination of unsaturated C-C bonds in a Markovnikov-addition manner in general followed by a nucleophilic addition with water. This work simplified the oxychlorination method with a mild chlorine source and a green oxygen source under ambient conditions.