Synthesis 2006(10): 1599-1612  
DOI: 10.1055/s-2006-926463
PAPER
© Georg Thieme Verlag Stuttgart · New York

Beckmann Rearrangement Using Indium(III) Chloride: Synthesis of Substituted Oxazoloquinolines from the Corresponding Ketoximes of 3-Acyl-1H-quinolin-4-ones

Kwang Ho Yoo, Eun Bok Choi, Hyeon Kyu Lee, Guy Hwan Yeon, Hee Cheol Yang, Chwang Siek Pak*
Korea Research Institute of Chemical Technology, Yusung-Ku Jang-Dong 100, Taejeon 305-600, Korea
Fax: +82(42)8600307; e-Mail: cspak@krict.re.kr;
Further Information

Publication History

Received 19 October 2005
Publication Date:
27 April 2006 (online)

Abstract

Nitrilium ion intermediates in the Beckmann rearrangement of 3-acyl-4-quinolinone ketoximes, in the presence of InCl3, were trapped by the β-hydroxy group of the tautomeric form of the ketoxime giving, predominantly, the corresponding oxazoloquinolines with isooxazoloquinolines formed as minor products.

1

Drug Data Rep. 2000, 22, 455.

2

Drug Data Rep. 2002, 24, 1033.

3

Drug Data Rep. 1998, 20, 938.

4

Drug Data Rep. 1991, 13, 591.

19

We could not reproduce the result claimed by Barman et al. in ref. 11a. When the same substrate, o-hydroxyaceto-phenone ketoxime, was subjected to the reaction conditions described therein, a mixture of benzoxazole (68%), benzisooxazole (6%), and 2-hydroxy acetanilide (20%) were obtained within 2 hours. However, 2-hydroxyacetanilide, prepared separately, was converted only sluggishly to benzoxazole (47%) under the same reaction condition in 30 hours. Additionally, 3-chloro- and 3,5-dichloro-2-hydroxy acetophenone ketoxime resulted in a mixture of the corresponding benzoxazole (81% and 73%) and benzisooxazole (7% and 8%) respectively without any corresponding acetanilide.

27

X-ray crystal structure analysis of 2e and 3i: atomic coordinates, bond lengths [Å] and angles [deg], anisotropic displacement parameters, hydrogen coordinates, torsion angles [deg] have been deposited at Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK, under deposition number CCDC 273870 for 2e, CCDC 273871 for 3i [fax: +44(1223)336033], E-mail: deposit@ccdc.cam.ac.uk).