Hydrochlorination stereoselectivity

Hydrochlorination of acetylallene in the presence of N,N -dimethylhydrazine dihydrochloride leads stereoselectively to the corresponding p-chloroenone that is a valuable intermediate in organic synthesis.4... 

Hydrochlorination Addition of hydrochloric acid to ynones in the presence of FeS04 is stereoselective, the products from l-aryl-2-propyn-l-ones being predominantly ( )-P-chlorovinyl ketones. 

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]. 

---