π-Allyl-σ-carbamoylcarbonyliron complexes from benzylideneacetone. Synthesis and π—σ rearrangement

The chemistry of (1-azabuta-1,3-diene)tricarbonyliron(0) complexes

“…Also when PPh 3 is added to complexes 30, the major reaction product is (PPh 3 ) 2 (CO) 3 Fe. There was no evidence for a carbonyl substituted 1-azabuta-1,3-diene complex, which reflects the high reactivity of the weakly bound r-N-tetracarbonyliron(0) complexes (30).…”

“…This method also prevents the unwanted Michael additions of amines to the 1-oxabuta-1,3-diene and is particularly useful for the synthesis of complexes derived from ligands prone to polymerisation. Alternatively, 1-azabuta-1,3-diene complexes may be synthesised by treatment of (1-oxabuta-1,3-diene)tetracarbonyliron(0) complex (48) with boron trifluoride followed by reaction of the resulting adduct 49 with a primary amine (Scheme 10) [30,31]. In these examples, the reaction proceeds via formation of allylic complex 50, which is in equilibrium with g 2 -(1-azabuta-1,3-diene)tetracarbonyliron(0) complex (51) where co-ordination to the iron moiety occurs through the alkene part of the 1-azabuta-1,3-diene and not the nitrogen lone pair.…”

“…When the reaction mixture is warmed, CO loss occurs and formation of the g 4 -complexes (53) is observed. This final step of the reaction has been demonstrated to proceed via the intermediacy of the 16-electron r-N-imine complexes (52) [30][31][32][33].…”