A Novel Route to 5-Substituted 3-Isoxazolols. Cyclization of <i>N,O-</i>DiBoc β-Keto Hydroxamic Acids Synthesized via Acyl Meldrum's Acids
作者:Ulrik S. Sørensen、Erik Falch、Povl Krogsgaard-Larsen
DOI:10.1021/jo991409d
日期:2000.2.1
We have found that N, O-diBoc-protected beta-keto hydroxamicacids can be synthesized and cyclized to 5-substituted 3-isoxazolols without formation of any byproduct. We present a novel and versatile three-step procedure in which carboxylic acid derivatives are converted into acyl Meldrum's acids which, upon aminolysis with N, O-bis(tert-butoxycarbonyl)hydroxylamine, lead to the N, O-diBoc-protected