NEIGHBORING GROUP EFFECTS ON RATES OF THERMOLYSIS OF 4-AZIDOTHIAZOLES

Citation
E. Ceulemans et al., NEIGHBORING GROUP EFFECTS ON RATES OF THERMOLYSIS OF 4-AZIDOTHIAZOLES, Tetrahedron, 53(28), 1997, pp. 9657-9668
Citations number
18
Categorie Soggetti
Chemistry Inorganic & Nuclear
Journal title
ISSN journal
00404020
Volume
53
Issue
28
Year of publication
1997
Pages
9657 - 9668
Database
ISI
SICI code
0040-4020(1997)53:28<9657:NGEORO>2.0.ZU;2-Z
Abstract
Rate measurements for thermolysis of 4-azidothiazoles in p-xylene solu tion have identified neighbouring group effects from nitro (19-fold ra te increase), phenyliminomethyl (16), formyl (4.5) and acetyl (2.2) su bstituents in the 5-position. These effects are very similar in magnit ude to those measured for 3-azidothiophenes, whereas in azidobenzenes the rate increases are much larger, 5-Substituents in 4-azidothiazole which are capable of conjugative donation (phenyl, ethyl propenoate) a lso increased the reaction rate. The reactions involving neighbouring group participation led to cyclized products from the 4-azidothiazoles though not all of these products were stable under the thermolysis co nditions. (C) 1997 Elsevier Science Ltd.