Other Zn-Barbier Reactions Solvents, Activating Agents

4 Other Zn-Barbier Reactions Solvents, Activating Agents 

It will be demonstrated in this Section that the application of unusual solvents and/or activating agents has opened up new synthetic possibilities through Zn-Barbier reaction. 

Trimethylchlorosilane. The use of trimethylchlorosilane (TMSCl) as an activator for reactions of metallic zinc (5 molar equivalents of TMSCl and 10 molar equivalents of Zn in diethyl ether) was recently introduced [80] in the following reaction  

Several steroid ketones were reported to be deoxygenated in good yields by this method [80a] e.g. 5a-cholestan-3-one was converted in 69% yield to 5a-cholest-2-ene  

Zn/TMSCl was also used for a new method of five-membered ring annel-ation [81]. The mechanism probably involves free radical generation from ketones, followed by internal addition to a variety of 7i-unsaturated functions X 

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