Synthesis 2006(17): 2825-2830  
DOI: 10.1055/s-2006-942491
PAPER
© Georg Thieme Verlag Stuttgart · New York

Practical Synthesis of Urea Derivatives from Primary Amines, Carbon Monoxide, Sulfur, and Oxygen under Mild Conditions

Takumi Mizuno*, Masatoshi Mihara, Toshiyuki Iwai, Takatoshi Ito, Yoshio Ishino
Osaka Municipal Technical Research Institute, 1-6-50, Morinomiya, Joto-ku, Osaka 536-8553, Japan
Fax: +81(6)69638049; e-Mail: tmizuno@omtri.city.osaka.jp;
Further Information

Publication History

Received 16 March 2006
Publication Date:
13 July 2006 (online)

Abstract

A new and facile synthetic method for urea derivatives was developed under mild conditions, and contrasts with conventional preparation methods that need highly toxic reagents (phosgene) or severe reaction conditions. In our reaction system, N,N-dimethylformamide or dimethyl sulfoxide as solvent strongly accelerated the carbonylation of primary amines with sulfur under carbon monoxide (1 atm) at 20 °C to give the corresponding thiocarbamate salts. These salts were readily oxidized by molecular oxygen under similarly mild conditions to afford urea derivatives in good to excellent yields. This urea synthesis could also be applied to a new synthesis of aromatic ureas by use of 1,8-diazabicyclo[5.4.0]undec-7-ene in N,N-dimethylformamide.

3

The reaction of isocyanates with amines 2 is a typical synthetic method for the preparation of urea derivatives. However, isocyanates are also prepared from phosgene and primary amines 2.

29

In the previous report [25] of urea synthesis from primary amines and carbon monoxide with the use of a selenium catalyst, the same reaction pathway was suggested.

30

NMR data are not reported, as measurement of NMR spectra was difficult because of the very low solubility of 1h in organic solvents.