Regioselective Syntheses of 2- and 4-Formylpyrido[2,1-b]benzoxazoles was written by Li, Ke-Lai;Du, Zong-Bo;Guo, Can-Cheng;Chen, Qing-Yun. And the article was included in Journal of Organic Chemistry in 2009.Electric Literature of C9H9NO This article mentions the following:
O-Acetaminophenols I (R = H, Cl, Me, t-Bu, NO2, OMe, Ph) reacted with Vilsmeier reagent under Meth-Cohn conditions to yield 2-formylpyrido[2,1-b]benzoxazoles II unexpectedly besides the known compounds III. Refluxing III in acetic anhydride gave 4-formylpyrido[2,1-b]benzoxazoles IV, the regioisomers of II. II (R = H) and IV (R = H) were structurally characterized by X-ray crystallog. A mechanism for the formation of II involving sequential chlorination, dimerization, intramol. elimination of HCl to form the oxazole ring, formylation twice, and regioselective intramol. nucleophilic cyclization to construct the pyridone ring is proposed. In the experiment, the researchers used many compounds, for example, 2,5-Dimethylbenzoxazole (cas: 5676-58-4Electric Literature of C9H9NO).
2,5-Dimethylbenzoxazole (cas: 5676-58-4) belongs to benzoxazole derivatives. Benzoxazoles belong to the group of well-known antifungal agents with antioxidant, antiallergic, antitumoral and antiparasitic activity. It is found within the chemical structures of pharmaceutical drugs such as flunoxaprofen and tafamidis.Electric Literature of C9H9NO
Referemce:
Benzoxazole – Wikipedia,
Benzoxazole | C7H5NO – PubChem