Ring Opening of (Spiro[2.4]hepta-4,6-diene)tricarbonyliron:  A Revisit

1998-01-19T00:00:00Z (GMT) by Yuan-Te Fu Pei-Chi Chao Ling-Kang Liu
(Spiro[2.4]hepta-4,6-diene)tricarbonyliron (2) self-converts to the tethered acyl complex (CO)2FeC(O)CH2CH25-C5H4) (3) when refluxed for 1 h in common organic solvents. The reaction of 2 with an external electrophile (CPh3+, H+) opens the three-membered ring, resulting in the cation (η5-C5H4CH2CH2R)Fe(CO)3+ whose structure was determined by spectroscopic methods and confirmed by X-ray analysis of the PPh3 derivative (η5-C5H4CH2CH3)Fe(CO)2(PPh3)+. The reaction of 3 with a strong electrophile (CPh3+, Me+) affords the rotationally restricted Fe−(alkoxy)carbene cation (CO)2FeC(OR)CH2CH25-C5H4)+, which can be converted to the Fe−(anilino)carbene cation (CO)2FeC(NHPh)CH2CH25-C5H4)+.