Synthesis 2008(23): 3835-3845  
DOI: 10.1055/s-0028-1083222
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

A Novel Synthetic Route to 2-Arylalkanoic Acids by a Ruthenium-Catalyzed Chemoselective Oxidation of Furan Rings

Masahiro Noji, Haruka Sunahara, Ken-ichi Tsuchiya, Tôru Mukai, Ayako Komasaka, Keitaro Ishii*
Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
Fax: +81(42)4958783; e-Mail: ishiikei@my-pharm.ac.jp;
Further Information

Publication History

Received 25 July 2008
Publication Date:
14 November 2008 (online)

Abstract

An efficient two-step synthesis of 2-arylalkanoic acids from 1-arylalkanols is described. Firstly, 1-arylalkylfuran derivatives were synthesized in high yields by the metal triflate catalyzed Friedel-Crafts alkylation of 2-methylfuran with 1-arylalkanols without employing anhydrous conditions. The chemoselective oxidation of the furan ring in 1-arylalkylfurans to carboxylic acid was then investigated. In a solvent system of hexane-EtOAc/H2O (1:3:4), the furan ring was selectively oxidized with 7 equivalents of NaIO4 by using 0.5 mol% RuCl3 as catalyst to give 2-arylalkanoic acids in good yields. The selectivity of ruthenium oxidation was controlled by the solvent ratio of hexane-EtOAc.

23

The use of HPLC-grade EtOAc or MS4A-treated (to adsorb EtOH) HPLC-grade EtOAc gave almost the same results.