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
Gold- and Silver-Catalyzed Reactions of Propargylic Alcohols in the Presence of Protic Additives
作者:Matthew N. Pennell、Peter G. Turner、Tom D. Sheppard
DOI:10.1002/chem.201102830
日期:2012.4.10
secondary and tertiary propargylicalcohols undergo a Meyer–Schusterrearrangement to give enones at room temperature in the presence of a gold(I) catalyst and small quantities of MeOH or 4‐methoxyphenylboronic acid. The syntheses of the enone natural products isoegomaketone and daphenone were achieved using this reaction as the key step. The rearrangement of primary propargylicalcohols can readily be combined
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。
A General Procedure for the Synthesis of Enones via Gold-Catalyzed Meyer−Schuster Rearrangement of Propargylic Alcohols at Room Temperature
作者:Matthew N. Pennell、Matthew G. Unthank、Peter Turner、Tom D. Sheppard
DOI:10.1021/jo102263t
日期:2011.3.4
Meyer−Schuster rearrangements of propargylic alcohols take place readily at room temperature in toluene with 1−2 mol % PPh3AuNTf2, in the presence of 0.2 equiv of 4-methoxyphenylboronic acid or 1 equiv of methanol. Good to excellent yields of enones can be obtained fromsecondary and tertiary alcohols, with high selectivity for the E-alkene in most cases. A one-pot procedure for the conversion of primary
Neighboring Group Participation of Phosphine Oxide Functionality in the Highly Regio- and Stereoselective Iodohydroxylation of 1,2-Allenylic Diphenyl Phosphine Oxides
作者:Hao Guo、Rong Qian、Yinlong Guo、Shengming Ma
DOI:10.1021/jo8013462
日期:2008.10.17
iodohydroxylation of 1,2-allenylic diphenyl phosphine oxides, yielding (E)-2-iodo-3-hydroxy-1-alkenyl diphenyl phosphine oxides with very high stereoselectivity. The scope of this reaction was examined extensively. Notably, studies on the reactivity of optically active substrates indicated that the axial chirality in the starting allenes may be efficiently transferred to the center chirality of the