Iron Aminocarbene Complexes Containing a Double CC Bond in the N-Substituent: Preparation and Reactivity

Reaction of N,N-diallylbenzamide with Na2Fe(CO)4 and Me3SiCl afforded chelated cis-tricarbonyl[(η2-N-allyl-N-allylamino)(phenyl)carbene]iron(0) directly. The same reaction of N-(3-buten-1-yl)-N-methylbenzamide proceeded with migration of the double bond to the allylic position, giving a mixture of chelated cis-tricarbonyl[(η2-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-methylamino)(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.