Alkenes Silver cyanide

Tetrasubstituted alkenes. A new route to alkenes of this type involves as the initial step reaetion of ketones with 1 to form the tertiary alcohols 2. These alcohols are not acetylated under conventional methods, but are acetylated in satisfactory yields by acetyl chloride in the presence of silver cyanide. Reaction of 3 with organocopper reagents gives tetrasubstituted alkenes as a mixture of (E)- and (Z)-isomers, 4 and 5. The stereoselectivity of this reaction depends on the relative size of R and R. When R is more bulky than R, 5 is formed predominately. Both products can be halodesilylated to vinyl iodides 6 or 7 or to vinyl bromides by BrCN-AlCU. 

A further report has appeared on the conversion of glycosyl cyanobro-mides (such as 74) to fully substituted alkenes mercury(II) cyanide-silver... 

Silver nitrate—benzyl cyanide Specific for cis and trans alkenes 50... 

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