Ring Cleavage Reactions of Substituted 2-Isoxazolines by Pentacarbonyliron Under Ultraviolet Irradiation

Abstract

The photoirradiation of 3,5-disubstituted 2-isoxazolines and Fe(CO)5 in MeOH causes the N–O and C4–C5 bond cleavage to give two fragments of aldehydes and ketones, while that of 2-isoxazolines having no substituent at 5-position gives additional β-hydroxy- and β-methoxyketones.

Unusual transformations of 2-isoxazolines

“…34,36 The enamino ketone 40 can form from the complex 41 by cleavage at the N7O bond and subsequent elimination of the AcO-or EtO-groups to give the vinylnitrene complex (pathway A, Scheme 5) similar to the complex 31. An alternative pathway for obtaining the enamino ketones 40 33 (pathway B, Scheme 5), through elimination of AcOH and EtOH from isoxazolines with the intermediate formation of the corresponding isoxazoles 42 and their degradation by metal polycarbonyls has been described.…”