Triflic Acid Mediated Dealkylative Lactonisation via NMR-Observable Alkyloxonium Intermediates
作者:M. Paz Muñoz、Guy C. Lloyd-Jones
DOI:10.1002/ejoc.200800970
日期:2009.2
self-catalysed reaction with the pent-4-enoate to generate an oxonium triflate intermediate (rate ˜ kobsd.[TfOH]2[ester]1), possibly via the dimer (TfOH)2. The oxonium triflate intermediate then evolves to the ?-lactone according to unimolecular kinetics, liberating MeOTf in an SNi reaction. 2H-labelling experiments with TfOD suggest that the acid protonates the carbonyl moiety of the ester, with subsequent intramolecular