Borylation of Propargylic Substrates by Bimetallic Catalysis. Synthesis of Allenyl, Propargylic, and Butadienyl Bpin Derivatives
摘要:
Bimetallic Pd/Cu and Pd/Ag catalytic systems were used for borylation of propargylic alcohol derivatives. The substrate scope includes even terminal alkynes. The reactions proceed stererospecifically with formal S(N)2' pathways to give allenyl boronates. Opening of propargyl epoxides leads to 1,2-diborylated butadienes probably via en allenylboronate intermediate.
Synthesis of Benzyl-, Allyl-, and Allenyl-boronates via Copper-Catalyzed Borylation of Alcohols
作者:Lujia Mao、Kálmán J. Szabó、Todd B. Marder
DOI:10.1021/acs.orglett.7b00256
日期:2017.3.3
Alcohols are among the most abundant and readily available organic feedstocks in industrial processes. The direct catalytic functionalization of sp3 C–O bonds of alcohols remains the main challenge in this field. Here, we report a copper-catalyzed synthesis of benzyl-, allyl-, and allenyl-boronates from benzylic, allylic, and propargylic alcohols, respectively. This protocol exhibits a broad reaction
trisacetonitrile hexafluorophosphate 4, the Alder-ene type reaction of alkenes and internalalkynes provides an effective way to synthesize trisubstituted alkenes. Unlike most typical olefination protocols, this reaction is atom economical, and affords trisubstituted alkenes with defined olefin geometry. The regioselectivity can be explained invoking a steric argument based on the proposed mechanism. The
1,3-acyloxy migration of propargyl α-ketoesters and a carbonyl-ene cyclization of in situ generated allenyl esters. DFT calculations suggest that the copper salt might play dual roles as both chloride abstractor facilitating the generation of highly active gold catalyst and Lewis acid promoting the stepwise intramolecular carbonyl-enereaction.
已经开发了一种双金属协议,以从容易获得的炔丙基 α-酮酯构建 ( Z )-γ-亚烷基丁烯内酯化合物。它涉及金催化的炔丙基α-酮酯的1,3-酰氧基迁移和原位生成的丙二烯酯的羰基-烯环化。DFT 计算表明,铜盐可能起到双重作用,即促进高活性金催化剂生成的氯化物提取剂和促进逐步分子内羰基-烯反应的路易斯酸。
Efficient Synthesis of 4-Halo-2,5-dihydro-1,2-oxaphosphole 2-Oxides from 1,2-Allenylphosphonates and CuX2 and Subsequent Suzuki Cross-Coupling of the C-Cl Bonds
作者:Ning Xin、Shengming Ma
DOI:10.1002/ejoc.201200228
日期:2012.7
A convenient and efficientsynthesis of 4-halo-2,5-dihydro-1,2-oxaphosphole2-oxides through CuX2-mediated direct halocyclization of diethyl 1,2-allenylphosphonates was developed. The yields range from moderate to excellent. The efficiency of axial-to-central chirality transfer has also been studied. Further Suzukicross-coupling of the resulting vinylic chlorides with dicyclohexyl(2,4,6-trimethoxyphenyl)phosphane
Gold-Catalyzed Efficient Preparation of Linear α-Iodoenones from Propargylic Acetates
作者:Meng Yu、Guozhu Zhang、Liming Zhang
DOI:10.1021/ol070637o
日期:2007.5.1
Au(PPh3)NTf2 is needed to convert readily accessible propargylic acetates into versatile linear alpha-iodoenones in good to excellent yields. This reaction is easy to execute and has broad substrate scope. Good to excellent Z-selectivities are observed in the cases of aliphatic propargylic acetates derived from aldehydes.