An expeditious synthesis of methyl jasmonate

作者：Chapuis Christian^*; Cantatore Carole; de Saint Laumer Jean Yves

来源：Helvetica Chimica Acta, 2006, 89(6): 1258-1264.

DOI：10.1002/hlca.200690124

We present an efficient three-step, two-pot synthesis of methyl jasmonate (trans-1) based on Diels-Alder cycloaddition of cyclopent-2-enone (2) and chloroprene (= 2-chlorobuta-1,3-diene; 3d) in either CHCl3 or CH2Cl2, catalyzed by SnCl4 (0.2 mol-equiv.) at 20 degrees (75% yield). Subsequent ozonolysis of a cisltrans 55:45 mixture of the cycloadduct 4d in either CH2Cl2 or AcOEt at -78 degrees, followed by addition of Me2S and MeOH in the presence of NaHCO3, afforded, in 64% yield, a cisltrans 40:60 mixture of the known aldehyde 5c. The latter was reacted at -50 degrees under salt-free conditions with the propyl Wittig reactant to furnish 1 as a cis/trans 20:80 mixture ((E/Z) 3:97). Alternatively, a cis/trans 7:93 mixture ((E/Z) 4:96) was obtained in 88% yield from epimerized 5c (AcOH, H2O, 40 degrees; 99%) under usual Wittig conditions at -20 degrees.

• 出版日期2006