Polymer-supported 1,3-oxazolium-5-olates: synthesis of 1,2,4-triazoles.
A traceless synthesis of 3,5-disubstituted 1,2,4-triazoles has been developed on polymeric supports. The synthetic process utilizes immobilized mesoionic 1,3-oxazolium-5-olates (munchnones) as key intermediates in the 1,3-dipolar cycloaddition reaction. The initial step in the synthesis involves reductive alkylation of phenylglycine methyl esters with Ameba resin. The resulting immobilized amino acid esters were subsequently acylated with a variety of carboxylic acid chlorides and subjected to hydrolysis with 15% KOH to yield the polymer-bound carboxylic acids. Finally, the cycloaddition between diethyl diazocarboxylate or 4-phenyl-4H-1,2,4-triazoline-3,5-dione and the polymer-bound munchnones generated from the corresponding carboxylic acids afforded the polymer-bound 3,5-disubstituted 1,2,4-triazoles. Cleavage from the polymeric support using trifluoroacetic acid gave the desired 3,5-disubstituted 1,2,4-triazoles with excellent yield and high purity.
Samanta
Swapan K
SK
Viikki Drug Discovery Technology Center, Faculty of Pharmacy, P.O. Box 56 (Viikinkaari 5 E), FI-00014 University of Helsinki, Finland.
Yli-Kauhaluoma
Jari
J
D015394:Molecular Structure; D019301:Oleic Acid / Q000737:chemistry*; D010080:Oxazoles / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D014230:Triazoles / Q000138:chemical synthesis* / Q000737:chemistry* / Q000302:isolation & purification
D010080:Oxazoles; D011108:Polymers; D014230:Triazoles; C045575:1,2,4-triazole; D019301:Oleic Acid