Homologation of Alkyl Acetates, Alkyl Ethers, Acetals, and Ketals by Formal Insertion of Diazo Compounds into a Carbon–Carbon Bond
作者:Yoshihiro Nishimoto、Makoto Yasuda、Fei Wang、Junyi Yi
DOI:10.1055/a-1523-1551
日期:2021.11
Homologation of alkyl acetates, alkyl ethers, acetals, and ketals was accomplished via formal insertion of diazo esters into carbon–carbon σ-bonds. The combined Lewis acid InI3 with Me3SiBr catalyzed the homologation of alkyl acetates and alkyl ethers. That of acetals and ketals was catalyzed solely by the use of InBr3. The key point of the homologation mechanism is that the indium-based Lewis acids
Gold-Catalyzed Reactions between Alkenyldiazo Carbonyl Species and Acetals
作者:Vinayak Vishnu Pagar、Appaso M. Jadhav、Rai-Shung Liu
DOI:10.1021/jo400419d
日期:2013.6.7
In the presence of catalyst IPrAuSbF6 catalyst (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene), alkenyldiazo carbonyl species react with organic acetals to give E-configured alkyl 3,5-dimethoxy-5-pent-2-enoates stereoselectively. This reaction sequence comprises an initial Prins-type reaction, followed by gold carbene formation.
Rearrangement of Hydroxylated Pinene Derivatives to Fenchone-Type Frameworks: Computational Evidence for Dynamically-Controlled Selectivity
作者:Marcus Blümel、Shota Nagasawa、Katherine Blackford、Stephanie R. Hare、Dean J. Tantillo、Richmond Sarpong
DOI:10.1021/jacs.8b05804
日期:2018.7.25
An acid-catalyzed Prins/semipinacolrearrangementcascade reaction of hydroxylated pinene derivatives that leads to tricyclic fenchone-type scaffolds in very high yields and diastereoselectivity has been developed. Quantum chemical analysis of the selectivity-determining step provides support for the existence of an extremely flat potential energy surface around the transition state structure. This
the structure of the isocyanide. The use of an electron-deficient aryl isocyanide, such as 2c and 2d, is required to selectively obtain the monoinsertion product. When aryl isocyanides containing alkyl substituents, such as 2a and 2b, are employed, two molecules of the isocyanide are incorporated, and the double-insertion product is obtained. The reaction of tert-octyl isocyanide also induces a double
描述了布朗斯台德酸催化异氰化物正式插入缩醛的 CO 键。各种非环状和环状缩醛可以应用于催化插入以形成 α-烷氧基亚胺酸酯。官能团,例如硝基、氰基、卤素、酯和烷氧基,可以耐受所采用的反应条件。反应过程高度依赖于异氰化物的结构。需要使用缺电子的芳基异氰化物,例如 2c 和 2d,以选择性地获得单插入产物。当使用含有烷基取代基的芳基异氰化物,例如2a和2b时,引入两个分子的异氰化物,得到双插入产物。叔辛基异氰化物的反应也诱导了双重掺入,但随后的酸介导的断裂会导致 2-烷氧基亚胺酰氰化物。单插入产物 α-烷氧基亚胺酸酯可以很容易地水解为 α-烷氧基酯,从而实现缩醛的正式羰基化。