A Short and Efficient Synthesis of (R,R)-2-Methylcyclopropanecarboxylic Acid
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- 作者：Laurent Delhaye ; Alain Merschaert ; Pieter Delbeke ; Willy Briô ; ne
- 刊名：Organic Process Research & Development
- 出版年：2007
- 出版时间：July 2007
- 年：2007
- 卷：11
- 期：4
- 页码：689 - 692
- 全文大小：130K
- 年卷期：v.11,no.4(July 2007)
- ISSN：1520-586X
文摘
We report herein a short and efficient synthesis of (R,R)-2-methylcyclopropanecarboxylic acid via a Horner-Wadsworth-Emmons reaction involving commercially available (S)-propylene oxide and triethylphosphonoacetate (TEPA). The TEPA/base/propylene oxide stoichiometry was found critical to achievehigh yields. We therefore studied the TEPA anion formationand stability using in situ IR spectroscopy. The reaction yieldis strongly influenced by the counterion and solvent, whereashigh diastereoselectivities are always obtained. Under the bestexperimental conditions (HexLi/MeTHF/150 
C), crude (R,R)-2-methylcyclopropanecarboxylic acid is obtained in 85-90%yield with >98% trans selectivity.
C), crude (R,R)-2-methylcyclopropanecarboxylic acid is obtained in 85-90%yield with >98% trans selectivity.