The Adverse Effect of Benzannelation on the Aromaticity of Oxocinyl Anion: A Combined Experimental and Theoretical Study
Document Type
Article
Publication Date
8-1-2010
Description
A synthesis of 2H-1-benzoxocin from readily available compounds was accomplished. The potentially 'aromatic' π-excessive systems 2H-1-benzoxocinyl and 6H-dibenz[b,f]oxocinyl anions were generated from their corresponding conjugate acid precursors 7c and 8, respectively. It was found that 2H-1-benzoxocinide 3d lacks the type of π-frame stability associated with the parent 2H-oxocinide 1d and that the dibenzo analog 5b is more unstable than 3d. Both 3d and 5b undergo rapid structural reorganization to form their corresponding stable isomeric anions. We were able to characterize the proton-quenched products of these anions as the ring-opened structures 15 and 18, respectively. 1H-NMR and an ab initio calculation at the 6-31g* level indicated that, unlike the 'aromatic' parent 2H-oxocinide 1d and the aza analog 3c, 3d incorporates a non-planar oxocinyl ring in which the negative charge is primarily localized on the pentadienyl moiety of the ring, but also partial delocalization of π-electron density onto the benzene ring occurs.
Citation Information
Kasmai, Hamid S.; Wang, Xiaodong; Doan, Hanh N.; Femia, Josef F.; Yablonsky, Thad M.; Read, Mary E.; and Dutton, David T.. 2010. The Adverse Effect of Benzannelation on the Aromaticity of Oxocinyl Anion: A Combined Experimental and Theoretical Study. Helvetica Chimica Acta. Vol.93(8). 1532-1544. https://doi.org/10.1002/hlca.200900430 ISSN: 0018-019X