Synthesis of - 3,y-Unsaturated Nitriles

The methodology has been elegantly employed for the stereocontrolled synthesis of the side chain of steroids with natural configuration (Eq. 10.5) [5]. 

B-trans-l-Alkenyl-9-BBN undergoes facile reaction with the a-halo carbanion generated from chloroacetonitrile in the presence of potassium 2,6-di-tert-butyl- 

B-Alkenyl-9-BBN P,y-Unsaturated ester Yield (%) Isomeric purity (%) 

Unlike the synthesis of ( )-(3,y-unsaturated esters [7], internal ( )-9-alke-nyls-9-BBN do not react with N,N-dialkyl(dimethylsulfuranylidene)acetamide. This is attributed to the large steric bulkiness of both internal 9-alkenyl-9-BBN and N,N-dialkyl(dimethylsulfuranylidene)acetamide, which hinder the latter attack to internal 9-alkenyl-9-BBN. 

Murahashi S-I, Imada Y, Nishimura K, (1988) J Chem Soc Chem Commun 1578 

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