Dramatic effect of the metal cation in dealkylation reactions of phosphinic esters promoted by complexes of polyether ligands with metal iodides
Articolo
Data di Pubblicazione:
2001
Citazione:
Dramatic effect of the metal cation in dealkylation reactions of phosphinic esters promoted by complexes of polyether ligands with metal iodides / D. Albanese, D. Landini, A. Maia. - In: JOURNAL OF ORGANIC CHEMISTRY. - ISSN 0022-3263. - 66:10(2001), pp. 3249-3252.
Abstract:
Metal ion electrophilic catalysis has been revealed in dealkylation reactions of phosphinic esters 1-4 promoted by complexes of polyether ligands 5-7 with metal iodides MIn (Mn+ = Li+, Na+, K+, Rb+, Ca2+, Sr2+, Ba2+) in low polarity solvents (chlorobenzene, l,e-dichlorobenzene, and toluene) at 60 degreesC. The catalytic effect increases with increasing the Lewis acid character of the cation, in the order Rb+ < K+ < Na+ < Li+ and Ba2+ < Sr2+ < Ca2+. The results are interpreted in terms of a transition state where the complexed cation (Mn+ subset of Lig) assists the departure of the leaving group Ph2P(O)O- and, at the same time, favors the attack at carbon of the nucleophile I- ("push-pull" mechanism). The rate sequence found for 1-4 (Me > Et much greater than i-Pr and t-Bu) shows that this reaction can be utilized for the selective dealkylation of these substrates.
Tipologia IRIS:
01 - Articolo su periodico
Elenco autori:
D. Albanese, D. Landini, A. Maia
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