Triyne alcohol

Synthesis of Natural Polyacetylenes.—Bohlmann and Weber have reported the synthesis of racemic samples of four polyacetylenic enol-ethers (43), (44), (45), and (46), isolated earlier from Anaphalis species (Scheme 2). The acetonide from the 3-hydroxydihydropyrone (40) was first converted into chloride (41) which with sodamide produced the acetylenic alcohol (42). Successive reaction (Cadiot-Chodkiewicz coupling) of bromohepta-1,3,5-triyne with (42) and treatment with base gave the cis- and /m jr-(43) enol-ethers, which reacted with thionyl chloride to produce cw-(44) and trans- A5)y respectively. Epoxidation of (45) then gave (46). In the same publication. 

Use of (PCy3)2Cl2Ru=CHPh (1) in Other Synthetie Transformations. As well as finding widespread use in metathesis, (1) has found applications as a catalyst for other important reactions. These include hydrosilylation of alk3Ties dehydrogenative condensation of alcohols and hydrosilylation of carbonyls intermolecular cyclotrimerization of terminal alkynes conversion of triynes to benzene derivatives Kharasch additions (Z)-selective cross-dimerization of ary-lacetylenes with silylacetylenes and hydrogenation of natural rubber. ... 

The second key building block, phosphonium salt 172, was prepared as outlined in Scheme 3.39. Iodide 163 was reacted in a copper(I)-catalyzed alkylation with the bisbromo-magnesium salt 164 to give triyne 165 in 90% yield. Reduction of the propargylic alcohol 165 to allylic alcohol 166 was achieved with lithium aluminum hydride (LAH), and then a... 

The tetralin-lactone framework of clyptoacetalide was assembled via cyclotri-merization of triyne intermediate 369, while the naphthalene-fused lactone core of danshenspiroketallactone, 374, was constructed via directed metallation and subsequent lactonization of the diethylamide 372. In each case, irradiation of the free alcohol in the presence of iodobenzene diacetate and iodine (i.e., Suarez oxidation conditions [185,186]) afforded the spirocyclic lactone as an inseparable mixture of the natural product and its epimer. 

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