6-PI-ELECTROCYCLIZATION OF AZAHEXA-1,3,5-TRIENES - A NEW ENTRY TO A REGIOSPECIFIC SYNTHESIS OF 3-ARYL(HETEROARYL)PYRIDINES

Authors
MOLINA P PASTOR A VILAPLANA MJ
Citation
P. Molina et al., 6-PI-ELECTROCYCLIZATION OF AZAHEXA-1,3,5-TRIENES - A NEW ENTRY TO A REGIOSPECIFIC SYNTHESIS OF 3-ARYL(HETEROARYL)PYRIDINES, Tetrahedron, 49(35), 1993, pp. 7769-7778
Citations number
19
Categorie Soggetti
Chemistry Inorganic & Nuclear
Journal title
Tetrahedron → ACNP
ISSN journal
00404020
Volume
49
Issue
35
Year of publication
1993
Pages
7769 - 7778
Database
ISI
SICI code
0040-4020(1993)49:35<7769:6OA-AN>2.0.ZU;2-X
Abstract
Aza Wittig reaction of iminophosphoranes derived from ethyl alpha-azid o-beta-aryl(pyrazolyl)propenoates with alpha,beta-unsaturated aldehyde s leads to aldimines which by heating undergo electrocyclic ring-closu re through the 3-azahexa-1,3,5-triene moiety to give 3-aryl(pyrazolyl) pyridines in a completely regiospecific fashion. However, iminophospho ranes derived from ethyl alpha-azido-beta-furyl(thienyl)propenoates fu rnish a mixture (1.2:1 ratio) of the corresponding furo- or thieno-pyr idine(2-azahexa-1,3,5-triene electrocyclization product) and 3-furyl(t hienyl)pyridine(3-azahexa-1,3,5-triene electrocyclization product).