Regio‐ and Stereoselective Construction of Cyclic‐ gem ‐Dihalo Frameworks via a Regio‐Inverse, Halo‐Hydration of Vinyl Halides

Herein, we report the discovery and development of a practically simple regio‐inverse, halo‐hydration of the cyclic‐vinyl halides by employing NXS–H ₂ O system for the rapid creation of gem ‐dihalomethane functional groups. This transformation involves the regioselective, tetra‐functionalization of the alkyne by constructing four bonds (C─C, C─O, and 2C─X/Y) and a ring in cascade manner. It is very robust and was also extended for the highly diastereoselective construction of molecular frameworks with gem ‐diheterohalomethane‐based chiral centers (but as racemic mixture). This modification of gem ‐diheterohalomethane construction represents the first example on the incorporation of four different groups on to the alkyne carbons with the concurrent, creation of two chiral centers. Furthermore, this strategy represents an example of regio‐reverse, halo‐hydration of vinyl halides (unknown in the literature) to give the gem ‐halogenation instead of vicinal‐halogenation (traditional reactivity) of vinyl halides.