Regioselective Syntheses of 2-and 4-Formylpyrido [2, 1-b] benzoxazoles

KL Li, ZB Du, CC Guo, QY Chen

Index: Li, Ke-Lai; Du, Zong-Bo; Guo, Can-Cheng; Chen, Qing-Yun Journal of Organic Chemistry, 2009 , vol. 74, # 9 p. 3286 - 3292

Full Text: HTML

Citation Number: 15

Abstract

o-Acetaminophenols (2) reacted with Vilsmeier reagent under Meth-Cohn conditions to yield 2-formylpyrido [2, 1-b] benzoxazoles (5) unexpectedly besides the known compounds 2- (benzoxazol-2′-yl)-3-dimethylaminoacroleins (4). Refluxing 4 in acetic anhydride gave 4- formylpyrido [2, 1-b] benzoxazoles (6), an isomer of 5. Both 5a and 6a were structurally characterized by X-ray crystallography. A mechanism for the formation of 5 involving ...