据报道,氢化钌/布朗斯台德酸催化的串联序列可用于合成1,3,4,9-四氢吡喃[3,4- b ]吲哚(THPIs)和相关的氧环骨架。该过程被设计的前提是容易得到的烯丙基醚将经历连续的异构化,第一至烯醇醚(RU催化),然后到oxocarbenium离子(布朗斯台德酸催化)适合于内 环化栓系亲核体。该方法不仅为合成THPI的传统oxa-Pictet-Spengler反应提供了有吸引力的替代方法,而且还方便地获得THPI同类物和其他重要的乙环(如乙缩醛)。
The Influence of Heteroatom-substituted Methyl Groups and of Vinyl Groups (CR<sub>2</sub>=CR—) Attached to C-2 of 1,3-Dioxolanes on the Ease and Direction of Hydrogenolysis of the 1,3-Dioxolanes by AlH<sub>2</sub>Cl, AlH<sub>3</sub>, or LiAlH<sub>4</sub>
作者:H. A. Davis、R. K. Brown
DOI:10.1139/v71-422
日期:1971.8.1
AlH2Cl or AlH3 in diethyl ether at room temperature reduces 2-vinyl- or 2-[alkyl (or aryl) substituted vinyl]-1,3-dioxolanes to only the β,γ-unsaturated alkyl β-hydroxyethyl ether, the product expected from hydride ion addition to C-2 of the 1,3-dioxolane. The ease of hydrogenolysis increases with increasing alkyl (or aryl) substitution on the 2-vinyl group.LiAlH4 in diethyl ether at room temperature, or
2-甲基-1,3-二氧戊环的甲基上的杂原子取代基阻碍了 2-取代的 1,3-二氧戊环的醚溶液的 AlH2Cl 的氢解速率。杂原子在降低氢解容易度方面的有效性是 H < S < O < Br < NR2。这种延迟被认为是由于杂原子的电负性和/或一些 AlH2Cl 与杂原子的配位引起的过渡态不稳定导致中间氧碳离子。AlH2Cl 或 AlH3 在室温下乙醚中将 2-乙烯基-或 2-[烷基(或芳基)取代的乙烯基]-1,3-二氧戊环还原为仅 β,γ-不饱和烷基 β-羟乙基醚,预期产物是氢阴离子加成到 C-2 1,3-二氧戊环。
Synthesis of Short-Chain Alkenyl Ethers from Primary and Bio-sourced Alcohols via the Nickel-Catalyzed Hydroalkoxylation Reaction of Butadiene and Derivatives
Hydroalkoxylation of butadiene has been performed in the presence of nickel precatalysts associated with chelating diphosphine ligands. High butadiene conversions and selectivities forming alkyl butenyl ethers were obtained with low catalyst loading. Reactions were performed with a wide scope of primary alcohols including benzylic alcohol derivatives and bio‐sourced alcohols. In the same way, the scope