Photochemistry of 3- and 5-phenylisothiazoles. Competing phototransposition pathways.
5-Phenylisothiazole undergoes phototransposition via the electrocyclic ring closure-heteroatom migration pathway and by the N(2)-C(3) interchange reaction pathway. The latter route is enhanced by the addition of triethylamine (TEA) to the reaction medium and by increasing the polarity of the solvent. In addition to phototransposition, 5-phenylisothiazole also undergoes photocleavage to 2-cyano-1-phenylethenethiol which was trapped by reaction with benzyl bromide to yield 2-cyano-1-phenylethen-1-ylbenzyl thioether. 3-Phenylisothiazole also phototransposes by both reaction pathways, but the product distribution is not affected by the addition of TEA or by changing the solvent polarity.
Pavlik
J W
JW
Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA.
Tongcharoensirikul
P
P
D005021:Ethylamines; D007202:Indicators and Reagents; D007700:Kinetics; D015394:Molecular Structure; D010782:Photolysis; D013329:Structure-Activity Relationship; D013844:Thiazoles / Q000737:chemistry*
D005021:Ethylamines; D007202:Indicators and Reagents; D013844:Thiazoles; C016162:triethylamine