cobalt catalysts at 30 °C. The results of 18O-labeling experiments suggested that rearrangement of the alkoxycarbonyl group from the aniline nitrogen to the ortho position proceeded in an unprecedented [1,3] manner.
reported previously, our mechanistic studies including oxygen-18 labelling experiments indicate that the rearrangement of the alkoxycarbonyloxy group proceeds in [1,3]-manner. In this article, we discuss the overall picture of the cobalt-catalysed [1,3]-rearrangement reaction including details of the reaction conditions and substrate scope.
Rearrangement of Differentially Protected<i>N</i>-Arylhydroxylamines
作者:Achim Porzelle、Michael D. Woodrow、Nicholas C. O. Tomkinson
DOI:10.1002/ejoc.200800672
日期:2008.10
The rearrangement of a series of N,O-difunctionalized N-arylhydroxylamines to generate protected 2-aminophenols has been investigated. N-Boc-N-aryl-O-acylhydroxylamines are stable, isolable compds. which rearrange smoothly at temps. between 110 and 140°C. The corresponding N-Boc-N-aryl-O-sulfonylhydroxylamines were not isolated and rearrange to 1,2-difunctionalized aminophenols at room temp. in excellent
Synthesis of Benzoxazolones from Nitroarenes or Aryl Halides
作者:Achim Porzelle、Michael D. Woodrow、Nicholas C. O. Tomkinson
DOI:10.1021/ol902885j
日期:2010.2.19
A simple and effective method for the preparation of benzoxazolones from nitroarenes or aryl halides is described. Partial reduction of a nitro group in the presence of a chloroformate followed by a microwave-assisted rearrangement/ring closure sequence provides a convenient and practical procedure to prepare this important pharmacophore. Rearrangement precursors were also accessed from aryl halides through transition-metal-catalyzed coupling.
Facile Procedure for the Synthesis
of <i>N</i>-Aryl-<i>N</i>-hydroxy
Carbamates
An efficient 1-pot procedure for the Zn-mediated redn. of nitro arenes in the presence of chloroformates leading to the corresponding N,O-bisprotected hydroxylamine is described. Reactions proceed smoothly under ambient conditions in THF-water mixts. in good to excellent yield (34-81%). Solvolysis of the bisprotected hydroxylamines with NaOMe at room temp. provides access to synthetically versatile