A convenient synthesis of crystalline 4-ethyl-2,3-dioxopiperazine-1- carboxamido-p-hydroxyphenylacetyl chloride using triphosgene

Department of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan,

Shanxi 030024, P. R. China

E-mail: weiwenlong@tyut.edu.cn        Fax: 86-351-6111165

Manuscript received 26 December 2006, revised 16 October 2007, accepted 26 November 2007

The crystalline 4-ethyl-2,3-dioxopiperazinc-1-carboxamido-p-hydroxyphcnylacetyl chloride was prepared in 97.6% yield when triphosgenc was reacted with D(-)-2-[(4-ethyl-2,3-dioxo-I-piperazineyl)-carbonylamino]-2-(4-bydroxypbenyl)acetic acid (HO-EPCP) in methylene dichloride at 0-5 ºC in the presence of triethylamine (TEA). This new method without using chlorinating agent such as phosgene, diphosgene, phosphorus oxychloride or oxalyl chloride enjoys a number of advantages in that the reaction is carried out under mild conditions and is clean.