" Isolated yield. 1-butene afford 5-phenyl-6-heptenenitrile (0" C, 1 h, 88%) and 6- octenenitrile (0" C, 1 h, 85% cis/trans mixture), respectively. In both cases, less than 4% of the SN2 substitution products was dete~ ted.'~ Typical Procedure. A suspension of 1.7 g (26 mmol) of zinc (99.99% purity) in 2 mL of THF containing 190 mg (1.0 mmol) of 1, Zdibromoethane was heated to 65" C for a minute and cooled to 25" C, and 0.1 mL (0.8 ...