Iron dichloride induced isomerization or reductive cleavage of isoxazoles: A facile synthesis of 2-carboxy-azirines
摘要:
5-Alkoxy-isoxazoles and N,N-disubstituted-5-isoxazolamines were found to isomerize to azirine derivatives by the use of iron dichloride as catalyst. On the contrary 5-alkyl- and 5-aryl-isoxazoles in the presence of the same salt, undergo reductive cleavage to enaminoketones. A common reaction intermediate is proposed. (C) 1997 Elsevier Science Ltd.
Dearomative [3+2] annulation of 5-amino-isoxazoles with quinoneimineketals (QIKs) and quinonemonoacetals (QMAs) provided various indoline- or 2,3-dihydrobenzofuran-fused isoxazolines in moderate to good yields with excellent diastereoselectivities.