A Comparative Theoretical Study of the Pericyclic-pseudopericyclic Character in a Group of Cyclizations of Dienylketenes to Cyclohexadienones
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- 作者：A. Peñ ; a-Gallego ; J. Rodrí ; guez-Otero ; E. M. Cabaleiro-Lago
- 刊名：Journal of Physical Chemistry A
- 出版年：2007
- 出版时间：April 19, 2007
- 年：2007
- 卷：111
- 期：15
- 页码：2935 - 2940
- 全文大小：457K
- 年卷期：v.111,no.15(April 19, 2007)
- ISSN：1520-5215
文摘
A comprehensive B3LYP/6-31+G* study of the nature of 6
ages/gifchars/pi.gif" BORDER=0 > electrocyclizations of four different dienylketenes(2-furanyl, 2-pyrrolyl, cyclopenta-1,3-dienyl, and 2-thiophenyl-substituted ketenes) to corresponding cyclohexadienones was carried out. An analogous system ((3Z)-4-(3H-pyrrol-2-yl)buta-1,3-dien-1-one) was alsoanalyzed. For this purpose, the complete pathways were determined (reactants, products, transition states,and the IRC connecting reactants and products), and changes in different magnetic properties (magneticsusceptibility, ages/gifchars/chi.gif" BORDER=0 >, magnetic susceptibility anisotropy, ages/gifchars/chi.gif" BORDER=0 >anis, and the nucleus-independent chemical shifts, NICS)were monitored along the reaction profiles with a view to estimating the aromatization associated to theprocesses. We have also applied the ACID (anisotropy of the current-induced density) method with the sameintention. The deep analysis of the results indicates a pericyclic character of the processes for the dienylketenesdespite the relatively small NICS values in the transition states. Only the reaction of (3Z)-4-(3H-pyrrol-2-yl)buta-1,3-dien-1-one presents pseudopericyclic character due to the in-plane attack of the lone pair on nitrogen.