The reaction of αω-dodecatrienediylnickel with allene and reactions of the resulting bis-π-allylnickel intermediates with carbon monoxide and alkyl isocyanides

Abstract

A series of C₁₅, C₁₈, C₂₁, and C₂₄ bis-π-allylnickel complexes has been formed by the sequential addition of up to 4 mole equivalents of allene to αω-dodecatrienediylnickel. Treatment of these complexes with carbon monoxide afforded cyclic hydrocarbons from a coupling reaction. Mixtures of two dimethylenecyclohexadecatrienes and trimethylenecyclo-octadecatrienes were obtained from the C₁₈ and C₂₁ complexes, respectively. Analogous products were also obtained from the C₂₄ complex but could not be fully characterised. In contrast, addition of n-butyl isocyanide, followed by acid hydrolysis, gave 1 : 1 mixtures of ketones and hydrocarbons. After hydrogen-ation mixtures of two dimethylcycloheptadecanones and two trimethylcyclononadecanones were formed from the C₁₈ and C₂₁ complex, respectively. Experiments showed little selectivity in the formation of the C₁₈ complex.