1) The fundamental ring system 
Oxazole is the parent compound for a vast class of heterocyclic aromatic organic compounds. These are azoles with an oxygen and a nitrogen separated by one carbon. Oxazoles are aromatic compounds but less so than the thiazoles. Oxazole is a weak base; its conjugate acid has a pKa of 0.8, compared to 7 for imidazole. ==Preparation== Classical oxazo...
The fundamental ring system. ... (05 Mar 2000) ... 
Type: Term Pronunciation: ok′să-zōl Definitions: 1. The fundamental ring system of pyranoses.