| 摘要 |
<p>The present invention provides a process for preparing a compound of formula (I), wherein R represents C1-C4 alkyl; and X represents an alkyl, alkenyl, cycloalkyl, aryl, substituted aryl, heterocycle, or substituted heterocycle, comprising treating a compound of formula (II), with a suitable crown ether and a suitable base followed by addition of a compound of formula R-M+ wherein M+ is a suitable cation.</p> |
