Iron aminocarbene complexes containing a double C=C bond in the N-substituent: Preparation and reactivity

Reaction of N,N-diallylbenzamide with Na2Fe(CO)(4) and Me3SiCl afforded che lated cis-tricarbonyl[(eta (2)-N-allyl-N-allylamino)(phenyl)carbene]iron(0) directly. The same reaction of N-(3-buten-1-yl)-N-methylbenzamide proceede d with migration of the double bond to the allylic position, giving a mixtu re of chelated cis-tricarbonyl[(eta (2)-N-(2-butenyl)-N-methylamino)(phenyl )carbene]iron(0) and nonchelated tetracarbonyl[(N-(2-butenyl)-N-methylamino )(phenyl)carbene]iron(0). N-(3-Buten-2,2-dimethyl-1-yl)-N-methylbenzamide, in which migration of double bond is not possible, gave a mixture of E and Z isomers of nonchelated tetracarbonyl[(N-(2,2-dimethyl-3-butenyl)-N-methyl amino)(phenyl)carbene]iron(0), Thermolysis of the latter furnished 1-methyl -3,3-dimethyl-6-phenyl-1,2,3,4-tetrahydropyridine as the only product.