David J. Rowe
1975
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Journal
ChemInform
Abstract
Publisher Summary This chapter investigates the five-membered heterocyclic compounds with three hetero-atoms in the ring. 1-methyltriazoles is prepared using (trimethylsilyl)methyl azide [from (chloromethyl)trimethylsilane and sodium azide)], a synthetic equivalent of the highly explosive methyl azide and the cycloadduct readily undergoes protiodesilylation. An important azide in medicinal use is the “anti-AIDS” drug AZT from which a large number of triazoles have been prepared. The enol tautomer of a 1,3-dicarbonyl compound may act as 1,3-dipolarophile. 1,2,3-triazoles are formed from the 1,3-dipolar addition of a diazoalkane to a nitrile. Oxidative cyclization of bis(hydrazones) is the oldest established method of 1,2,3-tziazole synthesis. 1-hydroxy benzolyiazole (HOBT) is extensively used as a “coupling agent” in peptide synthesis, where it functions as both a catalyst and a racemization suppressant. The 4,5-diacyltdazolines formed by addition of aryl azides to trans-l,2-dibenzoyl and to diacetyl-ethylene are unstable and decompose to a variety of products. The trans-l,2-diacetylethylene reacts with a azide to give an enamine as the major product, formed via ring-opening of the triazoline