Insertion reacts.bis-pi-allylnickel complexes

Copeland, Alison Helen (1976) Insertion reacts.bis-pi-allylnickel complexes. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The potential use of bis-n-allylnickel complexes as intermediates inthe formation of medium and large ring ketones has been investigated. Treatment of such complexes with carbon monoxide or alkyl isocyanide has resulted in either an insertion reaction with formation of a cyclic ketone or imine,or coupling of the allyl groups with formation of cyclic hydrocarbons. Carbonylation of a 1:1 mixture of bia-allylnickel species, derived from the reaction of bis(cyclooctadiene)nickel with three and four equivalents of allene respectively, afforded trimethylenecycloheptanone in 20% yield, but no insertion product from the tetramer species was detected. No ketone products were detected when tert-butyl isocyanide was added to the mixture of bis-allyl species and the product mixture hydrolysed.A variety of new bis-n-allylnickel complexes has been formed by treatment of the a,w-dodecatrienylnickel complex with excess allene. Treatment of these complexes with carbon monoxide afforded hydrocarbonexclusively from a coupling reaction, while addition of n -butyl isocyanide yielded 1:1 mixtures of ketones and hydrocarbons on hydrolysis.Addition of n-butyl isocyanide to the a,w-octadienylnickel complex afforded a 1.6:1 mixture of seven and nine-membered ring ketones in 40 yield. Treatment of the complex with excess allene afforded new bis-nallylnickel complexes derived from the insertion of up to three equivalents of allene. Carbonylation of the new complexes afforded ketone insertion products but in poor yield and, similarly, only small amounts of insertion products were obtained when the complexes were treated with isocyanide.Insertion reactions of olefins and acetylenes with the a,co-dodecatrienylnickel complex have been investigated. Insertion was observed when acetylenes possessing electron withdrawing groups were added to the complex;products derived from the insertion of dimethyl acetylenedicarboxylate were isolated in up to 4$ yield. Insertion of olefins into the complex was not observed.

This record has no associated files available for download.