Cyanomethyl anion transfer reagents for diastereoselective Corey–Chaykovsky cyclopropanation reactions
作者:Renè Hommelsheim、Katharina J. Hock、Christian Schumacher、Mohanad A. Hussein、Thanh V. Nguyen、Rene M. Koenigs
DOI:10.1039/c8cc05602a
日期:——
A readily available and bench-stable cyanomethyl sulfonium salt was used in highly diastereoselective Corey–Chaykovsky cyclopropanationreactions of electron-poor olefins. This efficient method provides a rapid route to access densely functionalized cyclopropyl nitriles.
Novel thiourea-amine bifunctional catalysts for asymmetric conjugate addition of ketones/aldehydes to nitroalkenes: rational structural combination for high catalytic efficiency
A series of thiourea-amine bifunctionalcatalysts have been developed by a rational combination of prolines with cinchona alkaloids, which are connected by a thiourea motif. The catalyst 3a, prepared from L-proline and cinchonidine, was found to be a highly efficient catalyst for the conjugateaddition of ketones/aldehydes to a wide range of nitroalkenes (up to 98/2 dr and 96% ee). The privileged cinchonidine
Nucleophilic Difluoromethylation Using (Bromodifluoromethyl)trimethylsilane
作者:Alexey L. Trifonov、Artem A. Zemtsov、Vitalij V. Levin、Marina I. Struchkova、Alexander D. Dilman
DOI:10.1021/acs.orglett.6b01641
日期:2016.7.15
triphenylphosphine, and DMPU serves as a source of difluorinated phosphorus ylide Ph3P═CF2 under mild conditions. The system was used to effect nucleophilic difluoromethylation of ketones and nitro alkenes. The reaction efficiency is believed to be associated with Lewis acidic activation of the substrates by a silylium species formed upon generation of the phosphorus ylide.
Reducing-Agent-Free Convergent Synthesis of Hydroxyimino-Decorated Tetracyclic Fused Cinnolines via Rh<sup>III</sup>-Catalyzed Annulation Using Nitroolefins
作者:Pidiyara Karishma、Chikkagundagal K. Mahesha、Sanjay K. Mandal、Rajeev Sakhuja
DOI:10.1021/acs.joc.0c02729
日期:2021.2.5
A mild Rh-catalyzed method was developed for the synthesis of hydroxyimino functionalized indazolo[1,2-a]cinnolines and phthalazino[2,3-a]cinnolines by reductive [4 + 2] annulation between 1-arylindazolones and 2-aryl-2,3-dihydrophthalazine-1,4-diones with varied nitroolefins. The targeted oxime decorated tetracyclic fused cinnolines were synthesized via sequential C–H activation/olefin insertion/reduction
开发了一种温和的Rh催化方法,通过还原1-芳基吲唑酮和2-芳基-[4 + 2]环合反应,合成羟基亚氨基官能化的吲唑并[1,2- a ] cinnolines和邻苯并[2,3- a ] cinnolines。 2,3-二氢酞嗪-1,4-二酮与各种硝基烯烃。在无还原剂的条件下,通过连续的C–H活化/烯烃插入/还原反应,合成了目标肟肟修饰的四环稠合肉桂醛。
4-Aminothioureaprolinal Dithioacetal as a Catalyst for Highly Enantioselective Michael Additions of Ketones and Aldehydes to Nitroolefins
4-Aminothioureaprolinal dithioacetal 4a is a highlyefficientcatalyst for the asymmetric Michaeladdition of ketones and aldehydes to nitroolefins requiring only 3 mol-% catalyst loading. The reactions proceeded smoothly and gave syn selective adducts with excellent yields (up to 98 % yield), diastereoselectivity (up to >99:1 dr), and enantioselectivity (up to 99 % ee) under solvent free conditions