US EPA

6850699 

Journal Article 

1,4-diaryl-1-azabuta-1,3-diene-catalyzed complexation of cyclohexa-1,3-diene by the tricarbonyliron fragment: Development of highly efficient catalysts, optimization of reaction conditions, and proposed mechanism 

Knolker, HJ; Knolker, HJ; Baum, E; Baum, E; Gonser, P; Gonser, P; Rohde, G; Rohde, G; Rottele, H; Rottele, H 

1998 

1 

Organometallics
ISSN: 0276-7333
EISSN: 1520-6041 

17 

18 

3916-3925 

10.1021/om980290g 

WOS:000075791000014 

The 1,4-diaryl-1-azabuta-1,3-diene-catalyzed complexation of cyclohexa-1,3-diene with either nonacarbonyldiiron or pentacarbonyliron is reported to provide high yields of the tricarbonyl(eta(4)-cyclohexa-1,3-diene)iron complex; This procedure enables exploitation of both tricarbonyliron fragments of nonacarbonyldiiron for the complexation of dienes for the first time. Using 12.5 mol % of 1-(4-methoxyphenyl)-4-phenyl-1-azabuta-1,3-diene and optimized reaction conditions (nonacarbonyldiiron, dimethoxyethane, reflux, 16.5 h, or pentacarbonyliron, dioxane, reflux, 45 h), a quantitative catalytic complexation of cyclohexa-1,3-diene is feasible with both reagents. An extensive study with a broad range of 1,4-diaryl-1-azabuta-1,3-dienes shows that the efficiency of the catalysts strongly depends on the substituents of the two aryl rings. Remarkably high activities are found for those catalysts deriving from condensation of cinnamaldehyde and ortho-methoxy-substituted arylamines. A hexacarbonyldiiron complex of 1-(4-methoxyphenyl)-4-phenyl-1-azabuta-1,3-diene is obtained as a byproduct of the catalytic complexation and is structurally confirmed by X-ray crystallography. A mechanism supported by the experimental findings is proposed.<