Synthesis of Agarofurans by Cyclization of 10-Epieudesmene-3,11-diols

Article abstract of DOI:10.1021/jo00138a010

The course of the direct cyclization of 10-epi- and 14-nor-10-epieudesm-4-ene-3,11-diols (2, 5) to α-agarofuran (1) and its derivatives has been investigated in detail.The reaction of 10-epieudesm-4-ene-3α,11-diol (9) with Jones reagent, p-toluenesulfonic acid, diethyl azodicarboxylate-triphenylphosphine, or p-toluenesulfonyl chloride affords 1 in variable yields.The 3-epimer of diol 9 (8) also affords 1 under similar conditions.The 14-nor analogues of diols 8 and 9 (12, 13) were prepared and have been found to afford 14-nor-α-agarofuran (14) with p-toluenesulfonic acid and to afford mixtures containing variable amounts of 14 with Jones reagent.The preparation in good yield of 14-nor-9-oxo-α-agarofuran (4), an intermediate in the synthesis of polyhydroxyagarofurans, is described.The stereochemistry of diols 8 and 9 has been confirmed, and a variety of minor reaction products from the cyclizations reactions have been characterized.