Revisiting the concept of the (a)synchronicity of diels‐alder reactions based on the dynamics of quasiclassical trajectories |
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| Authors: | Miguel A F de Souza Elizete Ventura Silmar A do Monte José M Riveros Ricardo L Longo |
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| Institution: | 1. Instituto De Química, Universidade Federal Do Rio Grande Do Norte, Natal, Rio Grande do Norte, Brazil;2. Departamento De Química, CCEN, Universidade Federal Da Paraíba, Jo?o Pessoa, Paraíba, Brazil;3. Departamento De Química Fundamental, Universidade Federal De Pernambuco, Recife, Pernambuco, Brazil;4. Instituto De Química, Universidade De S?o Paulo, S?o Paulo, Brazil;5. Centro De Ciências Naturais E Humanas, Universidade Federal Do ABC, Santo André, S?o Paulo, Brazil |
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| Abstract: | A number of model Diels‐Alder (D‐A) cycloaddition reactions (H2C?CH2 + cyclopentadiene and H2C?CHX + 1,3‐butadiene, with X = H, F, CH3, OH, CN, NH2, and NO) were studied by static (transition state ‐ TS and IRC) and dynamics (quasiclassical trajectories) approaches to establish the (a)synchronous character of the concerted mechanism. The use of static criteria, such as the asymmetry of the TS geometry, for classifying and quantifying the (a)synchronicity of the concerted D‐A reaction mechanism is shown to be severely limited and to provide contradictory results and conclusions when compared to the dynamics approach. The time elapsed between the events is shown to be a more reliable and unbiased criterion and all the studied D‐A reactions, except for the case of H2C?CHNO, are classified as synchronous, despite the gradual and quite distinct degrees of (a)symmetry of the TS structures. © 2015 Wiley Periodicals, Inc. |
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| Keywords: | cycloaddition mechanism dynamics synchronicity temporal dependence |
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