Significant acceleration of 6 pi-azaelectrocyclization resulting from a remarkable substituent effect and formal synthesis of the ocular age pigment A2-E by a new method for substituted pyridine synthesis

K Tanaka; H Mori; M Yamamoto; S Katsumura

doi:10.1021/jo005779+

Significant acceleration of 6 pi-azaelectrocyclization resulting from a remarkable substituent effect and formal synthesis of the ocular age pigment A2-E by a new method for substituted pyridine synthesis

J Org Chem. 2001 May 4;66(9):3099-110. doi: 10.1021/jo005779+.

Authors

K Tanaka¹, H Mori, M Yamamoto, S Katsumura

Affiliation

¹ School of Science, Kwansei Gakuin University, Uegahara, Nishinomiya, Hyogo 662-8501, Japan.

PMID: 11325275
DOI: 10.1021/jo005779+

Abstract

The remarkable acceleration of 6 pi-azaelectrocyclization due to the combination of the C4-carbonyl and the C6-alkenyl or phenyl substituents in 1-azatrienes was found. This observation was rationalized by considering the remarkable orbital interaction between the HOMO and LUMO of 1-azatrienes, which were obtained by molecular orbital calculations. The formal synthesis of the unusual retinal metabolite, A2-E, was achieved by two types of the new one-pot synthesis of substituted pyridines by utilizing the obtained facile 6 pi-azaelectrocyclization, one of which is compatible with the proposed metabolic pathway of A2-E.