- Nickel-catalyzed deallylation of aryl allyl ethers with hydrosilanes
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An efficient and mild catalytic deallylation method of aryl allyl ethers is developed, with commercially available Ni(COD)2 as catalyst precursor, simple substituted bipyridine as ligand and air-stable hydrosilanes. The process is compatible with a variety of functional groups and the desired phenol products can be obtained with excellent yields and selectivity. Besides, by detection or isolation of key intermediates, mechanism studies confirm that the deallylation undergoes η3-allylnickel intermediate pathway.
- Wang, Jingyang,Wang, Yu,Ding, Guangni,Wu, Xiaoyu,Yang, Liqun,Fan, Sijie,Zhang, Zhaoguo,Xie, Xiaomin
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- First total synthesis of rhuscholide A, glabralide B and denudalide
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The first total synthesis of rhuscholide A, a benzofuran lactone possessing anti-HIV-1 activity, had been accomplished in 14 linear steps with 10.6% overall yield. In this synthesis, base-mediated phenol ortho-alkylation and piperidine promoted aldol condensation were exploited as key steps. The synthesis was flexible and allowed for the convenient preparation of two analogous natural products glabralide B and denudalide.
- Li, Tian-Ze,Geng, Chang-An,Chen, Ji-Jun
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supporting information
(2019/08/27)
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- Selective cleavage of allyl and propargyl ethers to alcohols catalyzed by Ti(O-i-Pr)4/MXn/Mg
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(Chemical Equation Presented) Allyl and propargyl ethers were effectively deallylated or depropargylated to the parent alcohols via a C-O bond cleavage catalyzed by a low-valent titanium reagent (LVT), Ti(O-i-Pr)4/TMSCI/ Mg or Ti(O-i-Pr)4/MgBr2/Mg, under mild reaction conditions. Differentiation between the allyl and propargyl ethers was achieved by the reaction in the presence of AcOEt as an additive. The reagent also catalyzed intra- and intermolecular cyclotrimerization reactions of alkynes to substituted benzenes.
- Ohkubo, Mutsumi,Mochizuki, Sayaka,Sano, Takeshi,Kawaguchi, Yuuki,Okamoto, Sentaro
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p. 773 - 776
(2007/10/03)
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- Palladium charcoal-catalyzed deprotection of O-allylphenols
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Allyl aryl ethers can be easily cleaved by the use of 10% Pd/C under mild and basic conditions. The present reaction would involve a SET process rather than a π-allyl-palladium complex. The scope and limitation of this new deprotective methodology is also described.
- Ishizaki, Miyuki,Yamada, Makoto,Watanabe, Shin-Ichi,Hoshino, Osamu,Nishitani, Kiyoshi,Hayashida, Maiko,Tanaka, Atsuko,Hara, Hiroshi
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p. 7973 - 7981
(2007/10/03)
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- 4-hydroxy-piperidine derivatives
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The present invention relates to 4-hydroxy-piperidine derivatives of the general formula wherein X denotes —O—, —NH—, —CH2—, —CH═, —CHOH—, —CO—, —S—, —SO— or —SO2—; R1-R4are, independently from each other, hydrogen, hydroxy, lower-alkyl-sulfonylamino, 1- or 2-imidazolyl or acetamido; R5-R8are, independently from each other, hydrogen, hydroxy, lower-alkyl, halogen, lower-alkoxy, trifluoromethyl or trifluoromethyloxy; a and b may be a double bond, provided that when “a” is a double bond, “b” cannot be a double bond; n is 0-2; m is 1-3; p is 0 or 1 and to pharmaceutically acceptable addition salts thereof. Compounds of the present invention are NMDA(N-methyl-D-aspartate)-receptor subtype selective blockers, which can be used in mediating processes underlying development of CNS including learning and memory formation and function.
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Page column 25
(2010/01/31)
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- Photochemistry of Substituted 4,4-Dimethoxy-2,5-Cyclohexadienones
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4,4-Dimethoxy-2,5-cyclohexadienones 9-14 were prepared from the corresponding hydroquinone monomethyl ethers by oxidation with thallium trinitrate in methanol. Irradiation of solutions of 9-13 in methanol with a broad band of UV light centered at 350 nm in a Rayonet reactor afforded 2-cyclopentenone derivatives 15-19 in moderate to excellent yields, whereas irradiation of 14 in methanol gave phenol 8 along with other unidentified products. Irradiation of 11-14 in benzene yielded substituted phenols. The plausible reaction pathways for the product formation are discussed.
- Hong, Fang-Tsao,Lee, Kung-Shing,Tsai, Yow-Fu,Liao, Chun-Chen
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