896732-86-8Relevant articles and documents
Trapping of unsaturated small molecules through cyclization with iron-iminophosphorane complexes
Kubo, Kazuyuki,Baba, Takayuki,Mizuta, Tsutomu,Miyoshi, Katsuhiko
, p. 3238 - 3244 (2008/10/09)
The iron-iminophosphorane-carbonyl complex Cp*(CO) 2Fe{P(NPh)(OMe)2} (1; Cp* stands for η5-C5Me5) reacted with the activated alkyne dimethyl acetylenedicarboxylate (DMAD) to give Cp*(CO)-Fe{P(OMe) 2N(Ph)C(CO2Me)C(CO2Me)C(O)}, in which the alkyne was trapped between the imino nitrogen and one carbonyl carbon to form a six-membered metallacycle. In contrast, 1 reacted with CO2 to afford aza-Wittig-type metathesis products, PhN=C=NPh and oxophosphorane (phosphonate) complex Cp*(CO)2Fe{P(O)(OMe)2}, probably via a four-membered aza-phosphacycle as an intermediate. Free acetonitrile did not react with 1, while the coordinated acetonitrile in [Cp*(CO)(NCMe) Fe{P(NHPh)-(OMe)2}]PF6 was incorporated into a five-membered metallacycle through a base-catalyzed rearrangement to give [Cp*(CO)Fe{P(OMe)2N(Ph)C(Me)N(H)}]PF6, in which the nitrile carbon was bonded to the imino nitrogen. It was proposed that this intramolecular cyclization reaction is initiated by the formation of the neutral iminophosphorane complex Cp*(CO)(NCMe)Fe{P(NPh)(OMe)2} as an intermediate, followed by the prompt nucleophilic attack of the resulting imino nitrogen to the carbon atom of the coordinated acetonitrile.
