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Synlett 1990; 1990(1): 44-46
DOI: 10.1055/s-1990-20981
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Reductive Cyclization of Ethyl 3-Allyloxy-2-bromopropionates with Chromium(II) Acetate to Tetrahydrofurans

Thomas Lübbers* , Hans J. Schäfer
  • *Organisch-Chemisches Institut der Universität Münster, Correns-Straße 40, D-4400 Münster, Federal Republic of Germany
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Publication Date:
08 March 2002 (online)

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Ethyl 3-allyloxy-2-bromo-3-ethoxypropionates 1, substituted on the allyl group, are cyclized with chromium(II) acetate in high yield to substituted tetrahydrofurans 2 (10 examples). Depending on the substituents, the ratio of cis:trans-2 (at C3,4) varies from 1:3.9 to 1:0.31. Similar diastereoselectivities are found for the cyclization of ethyl 2-bromo-3-ethoxy-3-(1-methyl-2-propenyloxy)propanoate (1b) with Bu3SnH or (Bu3Sn)2 or for the cyclization of the corresponding 3-allyloxy-3-ethoxy-2-ethoxycarbonylpropanoic acids 6 via the Kolbe electrolysis.