Carbanions. 20. Rearrangements in reactions of 5-chloro-4,4-diphenyl-2-pentyne, 1-chloro-5,5-dimethyl-2,2-diphenyl-3-hexyne, and 5,5-dimethyl-2,2-diphenyl-3-hexyne with alkali metals. Cation effects on migratory aptitudes of groups
Propargylsilanes as Reagents for Synergistic Gold(I)‐Catalyzed Propargylation of Carbonyl Compounds: Isolation and Characterization of σ‐Gold(I) Allenyl Intermediates
Reported herein is the isolation and characterization, for the first time, of a σ‐gold allenyl complex as an intermediate in gold catalysis. This intermediate was captured during the study of a novel gold(I)‐catalyzed propargylation of carbonyl compounds with propargylsilanes. Notably, the gold‐catalyzed propargylation reaction, which proceeds with aldehydes and ketones, can be driven to the formation
We present herein the first visible-light-driven hydrocarboxylation as well as carbocarboxylation of alkynes using CO2 via an iridium/cobalt dual catalysis. Such transformations provide access to various pharmaceutically important heterocycles in a one-pot procedure from readily available alkynes. Coumarins, 2-quinolones, and 2-benzoxepinones were directly accessed through a one-pot alkyne hydrocarboxylation/alkene
我们在此展示了第一个可见光驱动的烃羧化以及通过铱/钴双催化使用 CO2 的炔烃的羧化。这种转化提供了通过一锅法从容易获得的炔烃获得各种药学上重要的杂环的途径。通过一锅炔烃加氢羧化/烯烃异构化/环化序列直接获得香豆素、2-喹诺酮和 2-苯并氧杂环酮,其中 Ir 光催化剂起到双重作用,促进炔烃加氢羧化中的单电子转移和随后的能量转移烯烃异构化。此外,前所未有的钴羧化/酰基迁移级联使炔双官能化能够高效引入γ-羟基丁烯内酯。
Enantioselective Copper-Catalyzed Radical Cyanation of Propargylic C–H Bonds: Easy Access to Chiral Allenyl Nitriles
作者:Ronghua Lu、Tilong Yang、Xin Chen、Wenzheng Fan、Pinhong Chen、Zhenyang Lin、Guosheng Liu
DOI:10.1021/jacs.1c07190
日期:2021.9.15
The first enantioselective copper-catalyzed cyanation of propargylic C–Hbonds via radical relay was established using novel BoxOTMS ligands, providing an efficient and straightforward tool for the construction of structurally diverse chiral allenyl nitriles in good yields with excellent enantioselectivities. This reaction features high functional group tolerance and mild conditions. In addition, the
The combination of H-3[PW12O40]center dot nH(2)O (1 mol %) and Et3SiH led to the direct catalytic deoxygenation of propargyl alcohols, in which proper solvent selection Cl(CH2)(2)Cl vs CF3CH2OH was the key to obtaining better product yields. Under similar conditions, the deoxygenation of allyl alcohols proceeded to give thermodynamically stable alkenes with migration of the double bonds in good yields.
Copper-Catalyzed Enantioselective Radical Esterification of Propargylic C–H Bonds
作者:Xiaotao Zhu、Hongli Bao、Jiajia Xi
DOI:10.1055/a-2240-5349
日期:2024.5
The copper-catalyzedenantioselective radical esterification of propargylic C–H bonds with tert-butyl peroxybenzoate (TBPB) as an oxidizing agent and an oxygenated nucleophile is reported. This variant of the Kharasch–Sosnovsky oxidation allows for the asymmetric esterification of open-chain carbon radicals without excessive amounts of alkyne substrates under mild reaction conditions, achieving a one-step