Artículos de revistas
Gas-phase chemistry of acylium ions. Seven-to-five ring contraction of 1,3-dioxepane and 1,3-dioxep-5-ene
Registro en:
Journal Of Mass Spectrometry. John Wiley & Sons Ltd, v. 34, n. 6, n. 670, n. 676, 1999.
1076-5174
WOS:000081036900010
10.1002/(SICI)1096-9888(199906)34:6<670
Autor
Moraes, LAB
Kotiaho, T
Eberlin, MN
Institución
Resumen
As shown by pentaquadrupole triple-stage mass spectrometric and O-18-labeling experiments, two seven-membered cyclic acetals, 1,3-dioxepane and 1,3-dioxep-5-ene, fail to react by transacetalization with the gaseous acylium ions CH3C+=O and (CH3)(2)NC+=O. Instead, a novel and less exothermic but more kinetically favored reaction, seven-to-five ring contraction, occurs predominantly, and to great extents with the most reactive acylium ion, (CH3)(2)NC+=O. 1,3-Dioxepane yields O-acylated tetrahydrofurans; 1,3-dioxep-5-ene yields O-acylated 2,5-dihydrofurans. Copyright (C) 1999 John Wiley & Sons, Ltd. 34 6 670 676