(+)-Neomethynolide, the aglycone of a twelve-membered ring macrolide, neomethymycin, was totally synthesized via its 8,9-didehydro derivative. The synthesis also established the stereochemistry of neomethynolide at C-10, C-11, C-12, and 8,9-double bond which had remained unproved.
Reaction of epoxides with triphenylphosphine–thiocyanogen (TPPT): preparation of α-thiocyanatovinyl ketones, vic-dithiocyanates, and vic-dithiocyanatohydrins
作者:Yasumitsu Tamura、Tomomi Kawasaki、Hitoshi Yasuda、Noriko Gohda、Yasuyuki Kita
DOI:10.1039/p19810001577
日期:——
A number of epoxides smoothly react with TPPT under mild conditions to give α-thiocyanatovinylketones, vic-dithiocyanates, or vic-thiocyanatohydrins, depending on the structures of the epoxides used. The reactions proceed site- and stereo-specifically, to give α-thiocyanatovinylketones from αβ-epoxyketones, threo-dithio-cyanate from trans-epoxide, erythro-dithiocyanate from cis-epoxide, and vic-thiocyanatohydrins
Facile epoxidation of α,β-unsaturated ketones with cyclohexylidenebishydroperoxide
作者:Kavitha Jakka、Jinyun Liu、Cong-Gui Zhao
DOI:10.1016/j.tetlet.2006.12.104
日期:2007.2
Cyclohexylidenebishydroperoxide was successfully used as the oxygen source for the oxidation of α,β-unsaturatedketones for the first time. The corresponding epoxides were obtained in excellent yields under the Weitz–Scheffer reaction conditions.
Ultrasound-Assisted Epoxidation of Olefins and α,β-Unsaturated Ketones over Hydrotalcites Using Hydrogen Peroxide
作者:Unnikrishnan R. Pillai、Endalkachew Sahle-Demessie、Rajender S. Varma
DOI:10.1081/scc-120021028
日期:2003.7
Abstract An efficient ultrasound-assisted epoxidation of olefins and α,β-unsaturated ketones over hydrotalcite catalysts in the presence of hydrogenperoxide and acetonitrile is described. This general and selective protocol is relatively fast and is applicable to a wide variety of substrates.
Neomethynolide (1), the aglycone of a twelve-membered ring macrolide, neomethymycin, was totally synthesized in its optically active form via 8,9-didehydro-1. The construction of the skeleton was carried out by condensing a stereoselectively synthesized fragment, 4-t-butyldimethylsiloxy-5-(2-methoxyethoxymethoxy)3-methyl-1-hexyne, with Prelog-Djerassi lactonic ester, and mixed anhydride method was used for the lactonization of an intermediary hydroxy acid. The full stereochemistry of 1 was established by this synthesis.