Present in the form of cytotoxic chlorosulfolipids found in marine life, the vicinal dichloro motif is conspicuous in Nature and offers a plethora of exciting challenges for the synthetic chemist. In contrast to its natural abundance, the synthesis of this venerable unit is comparatively underexplored and often requires stoichiometric reagents or pre-functionalization of an existing π-bond. This absence in the organic chemist arsenal renders the development of new methodologies into this motif as urgently required. Based on the initial 1886 discovery made by Willgerodt that dichloro(phenyl)-λ3-iodane (PhICl2) is generated from bubbling Cl2(g) through iodobenzene, herein a catalytic paradigm where the hypervalent species is generated in situ has been established. The utilization of a readily available iodoarene, a chloride salt and a terminal oxidant offers mild conditions and presents a broad substrate tolerance. Comprehensive analysis of critical additives delineates the mechanism at hand and reveals a I(I)/I(III) manifold as operational. Moreover, inspired by the performance of lactate-based iodine catalysts in various vicinal difunctionalization, a chiral Willgerodt-type precursor was envisaged and a first asymmetric variant is presented.

I(I)/I(III) catalyzed vicinal dichlorination of alkenes

2019 Fall National Meeting

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