42080-75-1Relevant articles and documents
Direct Electrochemical P(V) to P(III) Reduction of Phosphine Oxide Facilitated by Triaryl Borates
Elias, Joseph S.,Costentin, Cyrille,Nocera, Daniel G.
, p. 13711 - 13718 (2018)
Triaryl borate Lewis acids facilitate the direct two-electron reduction of the P(V) center of triphenylphosphine oxide (TPPO) to the P(III) center of triphenylphosphine at faradaic efficiencies of 37%. Insight from direct P(V) to P(III) reduction is provided from cyclic voltammetry. The electrochemical reduction of TPPO proceeds through an unusual ECrECi mechanism in which the breaking of the phosphoryl bond in a two-electron-reduced association complex with the triaryl borate is rate-determining. The rate and faradaic efficiency for TPPO reduction are tuned by judicious choice of substituents on triaryl borate, with tris(4-methoxyphenyl) borate demonstrating the highest for both. These results suggest that an attractive route toward the roomerature reduction of phosphate for phosphorus reclamation is greatly facilitated by the stabilization of reduced phosphate intermediates through their association with Lewis acids.
Regio- and stereoselective ring opening of enantiomerically enriched 2-aryl oxetanes and 2-aryl azetidines with aryl borates
Bertolini, Ferruccio,Crotti, Stefano,Di Bussolo, Valeria,Macchia, Franco,Pineschi, Mauro
supporting information; experimental part, p. 8998 - 9007 (2009/04/11)
(Chemical Equation Presented) The regioselective ring opening of 2-aryl-substituted four-membered heterocyclic rings with phenols, including catechol, was achieved by the use of aryl borates in mild and neutral reaction conditions without the aid of any transition metal catalysts. While β-alkyl azetidines were found not to be reactive, optically active N-tosyl azetidines gave the corresponding β-aryloxy amines in a racemic form, thus indicating the considerable carbocationic character of the transition state. The introduction of a hydroxyl group in the azetidine ring (i.e., an azetidinol), able to anchor the aryl borate and to direct the subsequent nucleophilic delivery, was shown to determine the ring-opening process with predominant inversion of configuration. When enantiomerically enriched 2-aryl oxetanes were used, the reduced extent of racemization observed (up to 93:7 er) was rationalized by an intramolecular delivery through a six-membered transition state, giving β-aryloxy alcohols with a predominant retention of configuration (i.e., a syn-stereoselective ring opening). The aryloxy alcohols obtained, endowed with suitable functionalities, can be cyclized to give access to enantiomerically enriched 2-aryl-1,5-benzodioxepins.
Facile regio- and stereoselective carbon-carbon coupling of phenol derivatives with aryl aziridines
Pineschi, Mauro,Bertolini, Ferruccio,Crotti, Paolo,Macchia, Franco
, p. 2627 - 2630 (2007/10/03)
A chemo-, regio-, and stereoselective direct carbon-carbon coupling of readily available aryl borates with N-protected aryl aziridines provides a method for the synthesis of new 2-(o-hydroxyaryl)-2-aryl ethylamines which can be used, in a novel annulation
