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[2 + 3] Cycloaddition of C,C,N ‐triphenylnitrone to trans ‐substituted nitroethylenes in the light of an AM1 and AM1/COSMO computational study
Author(s) -
Baranski Andrzej,
Jasinski Radomir,
Żurowski Kazimierz
Publication year - 2003
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.612
Subject(s) - chemistry , cycloaddition , ring (chemistry) , acetonitrile , toluene , nitro , regioselectivity , computational chemistry , transition state , kinetic energy , acetone , medicinal chemistry , stereochemistry , organic chemistry , catalysis , alkyl , physics , quantum mechanics
AM1 calculations suggest that the [2 + 3] cycloaddition of triphenylnitrone 1 to nitroalkenes 2a – c in the gas phase takes place in a concerted manner. However, the azolidine ring bonds C3—C4 and O1—C5 are not formed fully synchronously. Kinetic factors favor the formation of cycloadducts with nitro group in position C‐4 of the azolidine ring (path A ). Introduction of toluene, acetone or acetonitrile as a reaction medium increases the activation barriers for both regioisomeric paths. Simultaneously, the energy profiles for path A undergo qualitative change. In this case, two transition states and an intermediate with zwitterionic character were localized by means of the AM1/COSMO method. Copyright © 2003 John Wiley & Sons, Ltd.