Organische Synthesen mit übergangsmetall‐Komplexen, 52 N ‐Vinylaminocarben‐ und N ‐(2‐Propenyl)aminocarben‐Komplexe durch Addition von Keteniminen an Carben‐Eisenkomplexe

Organic Syntheses with Transition Metal Complexes, 52 1) . ‐ N ‐Vinylaminocarbene and N ‐(2‐Propenyl)aminocarbene Complexes by Addition of Ketene Imines to Carbene Iron Complexes Ketene imines R(Me)C = C = NPh ( 2 , R = Me, Et, i ‐Pr) form 1 : 1 adducts with the carbene iron complex (CO) 4 ,FeC(OEt)Ph ( 1 ). The initial step of the reaction involves an attack of the nitrogen atom of 2 at the carbene carbon atom of 1 and a subsequent rearrangement to give N ‐vinylaminocarbene complexes ( E / Z )‐ 4 . In a parallel process with different regiochemistry the central carbon of the CCN unit is attached to the carbene carbon to yield π‐allyl,σ‐complexes ( E / Z )‐3. Alkylation of 3a with [Et 3 O]BF 4 leads to the formation of a cationic N ‐(2‐propenyl)‐aminocarbene complex 6a . Protonation of 4 with trifluoroacetic acid results in a ring contraction to give the four‐membered metallacycles 7 . X‐ray data are reported for prototypes (Z)‐ 4c and 6a .