A computational study of the formation and dimerization of benzothiet-2-one.
ABSTRACT A computational B3LYP/6-31G(d,p) study of the formation of benzothiet-2-one (4) from benzothiophenedione (2) and its subsequent dimerization to 5 was performed. The proposed intermediate ketene 3 has no gas-phase barrier to ring closure to 4. Three transition structures for dimerization were located. The geometry of the lowest energy one (TS8a) has a geometry corresponding to a two atom + two atom, face-to-face addition of the two thiolactone moieties. The orbital interactions suggest that the reaction is pseudopericyclic.
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ABSTRACT: This report surveys the 2007 literature on mechanisms of pericyclic reac-tions. One recurring theme in this year's reports is catalysis. Several studies addressed the catalysis of cycloaddition reactions by preorganization (via encapsulation, hydrogen bond directed precomplex formation, or hydro-phobic effects) or selective transition state stabilization (via hydrogen bonding interactions) and the acceleration of sigmatropic shifts by selective transition state stabilization (via hydrogen bonding, transition metal com-plexation, and weak interactions with halogens) or addition of an electron. In addition, the mechanisms of several interesting cascades consisting of multiple types of pericyclic reactions linked in tandem were examined in detail.