An Expeditious Synthesis of Methyl Jasmonate |
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Authors: | Christian Chapuis,Carole Cantatore,Jean‐Yves de Saint Laumer |
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Affiliation: | Christian Chapuis,Carole Cantatore,Jean‐Yves de Saint Laumer |
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Abstract: | 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° (75% yield). Subsequent ozonolysis of a cis/trans 55 : 45 mixture of the cycloadduct 4d in either CH2Cl2 or AcOEt at ? 78°, followed by addition of Me2S and MeOH in the presence of NaHCO3, afforded, in 64% yield, a cis/trans 40 : 60 mixture of the known aldehyde 5c . The latter was reacted at ? 50° 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°; 99%) under usual Wittig conditions at ? 20°. |
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Keywords: | Jasmonate, methyl Diels– Alder reactions Cycloadditions Ozonolysis Chloroprene |
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