Alkynes hydrochlorination

Hydrochlorination of Alkynes When Thomas and coworkers treated different alkynes in aqueous methanol with HAuC14 and observed the corresponding ketones as major products (Equation 8.28), with less than 5% of methyl vinyl ethers and vinyl chlorides, they were unaware of the fascinating treasure that was in front of them. Some of the most important types of products for gold catalysis were reported in the aforementioned study, but unfortunately at that time this process was believed to be a gold(III) oxidation process, despite the fact that the reaction achieved almost six turnovers. 

The formal hydrochlorination of alkynylboronates can be achieved through the use of Cp ZrCHICl followed by the addition of NCS (Scheme 6.44) [84], The chemistry was regioselective for the formation of the -isomer, and the yields of the chlorinated vinylboronates were fair to moderate. The incorporation of the chlorine was valuable since it provided a synthetic handle for further functionalization. A variation of this approach was used in the stereoselective hydroboration of terminal alkynes (Scheme 6.45) [85]. 

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