An ab Initio Study of a Retro-Wolff Rearrangement: From Diazafulvenone to Cyanovinyl Isocyanate without a Singlet α-Oxocarbene Intermediate

Nguyen M.T., Hajnal M.R., Tae-Kyu H., Vanquickenborne L.G. and Wentrup C. (1992) An ab Initio Study of a Retro-Wolff Rearrangement: From Diazafulvenone to Cyanovinyl Isocyanate without a Singlet α-Oxocarbene Intermediate. Journal of the American Chemical Society, 114 11: 4387-4390. doi:10.1021/ja00037a054


Author Nguyen M.T.
Hajnal M.R.
Tae-Kyu H.
Vanquickenborne L.G.
Wentrup C.
Title An ab Initio Study of a Retro-Wolff Rearrangement: From Diazafulvenone to Cyanovinyl Isocyanate without a Singlet α-Oxocarbene Intermediate
Journal name Journal of the American Chemical Society   Check publisher's open access policy
ISSN 1520-5126
Publication date 1992-05-01
Year available 1992
Sub-type Article (original research)
DOI 10.1021/ja00037a054
Open Access Status Not yet assessed
Volume 114
Issue 11
Start page 4387
End page 4390
Total pages 4
Place of publication WASHINGTON
Publisher AMER CHEMICAL SOC
Language eng
Abstract Ab initio molecular orbital calculations have been used to study the unimolecular rearrangement of diazafulvenone leading to cyanovinyl isocyanate. The geometries of stationary points were optimized at HF/6-31G** while relative energies were obtained from multireference configuration interaction (MRCISDQ) calculations with the 6-31G** basis set. A singlet oxocarbene structure was not found to be a local minimum but rather a transition structure connecting diazafulvenone to isocyanovinyl isocyanate, the latter molecule being a distinct intermediate during the rearrangement to cyanovinyl isocyanate. Diazafulvenone is calculated to lie 14 and 32 kcal/mol, respectively, above isocyano- and cyanovinyl isocyanate (Z conformers) and to be separated from the isocyanide form by an energy barrier of 44 kcal/mol. The diazafulvenone --> isocyanovinyl isocyanate interconversion, which can be regarded as a retro-Wolff rearrangement, is thus a concerted reaction without a discrete singlet oxocarbene intermediate. It also constitutes the rate-determining step of the entire rearrangement process, in agreement with experimental observation. As shown by an analysis of localized orbitals, the diazafulvenone --> isocyanovinyl isocyanate interconversion involves six electron pairs that circulate following a cyclic motion.
Keyword Basis-Sets
Ketene
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import - Archived
 
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