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Theoretical Study of Pericyclic Reactions of Nitrosoethylene and (Thionitroso)ethylene
Author(s) -
Sperling Dirk,
Mehlhorn Achim,
Reißig HansUlrich,
Fabian Jürgen
Publication year - 1996
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199619961018
Subject(s) - chemistry , pericyclic reaction , cycloaddition , ethylene , azirine , ab initio , computational chemistry , dimethyl acetylenedicarboxylate , reactivity (psychology) , pyrrole , ethylene oxide , ring (chemistry) , medicinal chemistry , organic chemistry , catalysis , copolymer , medicine , polymer , alternative medicine , pathology
Abstract Structure and reactivity of the title compounds 1 were examined by ab initio methods at the post Hartree‐Fock level of theory. Both compounds are expected to undergo electrocyclic ring closure to 4 H ‐1,2‐oxazete ( 4O ) and 4 H ‐1,2‐thiazete ( 4S ), respectively. The alternative electrocyclic reaction affording 2 H ‐azirine 1‐oxide ( 3O ) and 2 H ‐azirine 1‐thioxide ( 3S ) is definitely less favoured. (Thionitroso)ethylene ( 1S ) is more reactive than the oxygen‐containing congener. The same holds for the cycloaddition reaction with ethylene. [4 + 2] Hetero Diels‐Alder reactions furnishing 4 H ‐1,2‐oxazine ( 5O ) or 4 H ‐1,2‐thiazine ( 5S ) are favoured over the [3 + 2] cycloaddition reactions providing 2 H ‐pyrrole 1‐oxide ( 2O ) and 2 H ‐pyrrole 1‐thioxide ( 2S ). The results of RMP2/6‐31G * calculations and results obtained at lower levels of theory (RHF, PM3) are compared and discussed with respect to the experimental material available. Some additional single‐point calculations at the computationally more demanding QC1SD/6‐31G * level confirmed conclusions drawn from RMP2 calculations. Some test calculations also showed that the theoretical results are less affected by consideration of the temperature by statistic thermodynamics and by inclusion of solvent effects by a self‐consistent reaction‐field method.