Synthesis Of 4 (3H)-Quinazolinone And 1,2,4-Oxadiazole Derivatives Promoted By Imidazole Hydrochloride

Imidazole hydrochloride as an environmentally benign catalyst has been utilized in our previous works to develop methodologies for synthesis of benzimidazole,benzoxazole and benzothiazole derivatives in high efficiency.As a continuous exploration of its application in synthetic chemistry,methodologies for synthesis of 4(3H)-quinazolinones and1,2,4-oxadiazoles promoted by imidazole hydrochloride are developed and described in two parts in this paper.Part 1: Synthesis of 4(3H)-quinazolinones4(3H)-quinazolinone nucleus is endowed with enormous bioactive potential,its derivatives widely prevail in natural compounds and pharmaceutical industry.Emergence of drug resistance poses a major threat to our community,rendering the discovery and synthesis of novel4(3H)-quinazolinone derivatives against drug resistance so imperative.Tremendous effort has been made in developing methodologies for synthesis of 4(3H)-quinazolinones to achieve the unmet medicinal need alongside criteria of green chemistry.In the light of our previous work in synthesis of benzimidazole,benzoxazole and benzothiazole derivatives,imidazole hydrochloride and similar synthetic route are applied into the reaction system of anthranilamides and DMF derivatives to afford desired products,4(3H)-quinazolinones.Part 2: Synthesis of 3,5-disubstituted-1,2,4-oxadiazolesFive-membered 1,2,4-oxadiazoles receive much attention only after 80 years since its first synthesis.Due to the weak oxygen-nitrogen bond and unique structure,1,2,4-oxadiazole tends to rearrange into structurally stable molecules with other properties,which expands the extension of1,2,4-oxadiazoles into multiple fields,such as medicinal chemistry,liquid crystals,energetic materials,and materials for OLEDs.From the perspective of green chemistry,developing an eco-friendly methodology for synthesis of1,2,4-oxadiazoles under simple conditions will undoubtedly furnish the oxadiazole chemistry.Methodology for synthesis of 3,5-disubstituted-1,2,4-oxadiazoles promoted by imidazole hydrochloride is developed.This protocol circumvents the use of coupling agents and strong base reported in previous literatures,which makes it an eco-friendly alternative for synthesis of3,5-disubstituted-1,2,4-oxadiazoles.