title: Mechanism of anionic dearomatizing reactions of diphenylphosphinamide derivatives: a theoretical and experimental study.
abstract: The mechanism of the anionic dearomatisation of phosphinamide derivatives has been investigated both theoretically and experimentally. The potential-energy surface of model reactions was studied at the Becke3LYP/6-31+G* level of theory, and according to this study, a pre-reactive complex is formed between the alkyllithium and the phosphinamide. This complex evolves preferentially through NC(alpha)-metalation of the phosphinamide. The intramolecular nucleophilic addition of the carbanion to the ortho position of the aromatic ring leads to the dearomatised products, in a reaction that has been shown to be under thermodynamic control. Coordinating co-solvents, such as hexamethyl phosphoramide (HMPA) or N,N'-dimethyl-N,N'-propylene urea (DMPU), appear to influence the reaction by favouring the formation of solvent-separated ion pairs. The cyclisation reaction of allylphosphinamide derivatives was also studied. It was found that both the alpha- and gamma-attack of the allyl anion can take place, however the formation of the seven-membered ring products derived from the gamma-attack are clearly favoured.
authors.affiliation: Departamento de Química Orgánica e Inorgánica, Universidad de Oviedo c/Julián Clavería 8, 33006 Oviedo, Spain.
authors.forename: Antonio Morán
authors.initials: AM
authors.lastname: Ramallal
authors.forename: Ignacio
authors.initials: I
authors.lastname: Fernández
authors.forename: Fernando
authors.initials: F
authors.lastname: López Ortiz
authors.forename: Javier
authors.initials: J
authors.lastname: González