Stereocontrolled Synthesis of Halovinylbenziodoxoles by Hydro- and Iodochlorination of Ethynylbenziodoxoles.

We report herein the synthesis of highly substituted and stereochemically well-defined vinylbenziodoxole (VBX) derivatives through hydrochlorination and iodochlorination of ethynylbenziodoxoles. The hydrochlorination is achieved using pyridine hydrochloride as an HCl source in an anti-fashion under mild, open-air conditions to afford a 2-chlorinated VBX product, which serves as a useful building block for the stereoselective synthesis of trisubstituted alkenes. Meanwhile, iodochlorination with iodine monochloride proceeds in an unusual syn-pathway, stereoselectively affording a tetrasubstituted VBX derivative.