Trifluoromethyl-p-tolyldiazomethane in 1,3-dipolar cycloaddition reactions
摘要:
Trifluoromethyl-p-tolyldiazomethane (I) forms [3 + 2]-cycloadducts with activated alkenes and alkynes. The products of these regiospecific reactions are substituted pyrazolines (II)-(VI) and pyrazoles (VIII)-(X). Reaction of (I) with fumarates, trifluoropyruvates and allyl chloride is accompanied by elimination of N2 and formation of a 1,2-bis(trifluoromethyl)stilbene. The results obtained indicate that (I) enters only the HOMO-controlled 1,3-dipolar addition reactions.
Synthesis of Trifluoromethylated Tetrasubstituted Allenes via Palladium-Catalyzed Carbene Transfer Reaction
作者:Chao Pei、Zhen Yang、Rene M. Koenigs
DOI:10.1021/acs.orglett.0c02638
日期:2020.9.18
Herein, we report on the palladium-catalyzedsynthesis of trifluoromethylated, tetrasubstituted allenes from vinyl bromides and trifluoromethylated diazoalkanes in good to excellent yield. This reaction proceeds via oxidative addition of a Pd(0) complex with vinyl bromide. Subsequent base-promoted reductive elimination generates the allene. This methodology provides an efficient strategy even on gram
Access to <i>gem</i>-Difluoro Olefins via C–H Functionalization and Dual Role of Anilines
作者:Zhen Yang、Chao Pei、Rene M. Koenigs
DOI:10.1021/acs.orglett.0c02568
日期:2020.9.18
In this Letter, we describe a simple, practical approach in which cheap CuI was used as a catalyst to introduce a gem-difluoro olefin onto simple electron-rich aniline derivatives in good yield via direct C–H functionalization and a subsequent HF elimination reaction. Detailed mechanistic studies point at a dual role of aniline derivatives in this reaction, which serve as a substrate and a basic promoter
An asymmetric copper(I)-catalyzed Si-H insertionreaction of 1-aryl-2,2,2-trifluoro-1-diazoethanes in dimethyl carbonate as a green solvent alternative was developed. A C2-symmetric copper(I) diimine complex enabled the asymmetric insertionreaction to give enantioenriched (1-aryl-2,2,2-trifluoroethyl)silanes with excellent stereoselectivities (up to 98:2 er). Successful conversion of the silanes into
Enantioselective rhodium-catalysed insertion of trifluorodiazoethanes into tin hydrides
作者:Stephen Hyde、Janis Veliks、David M.H. Ascough、Robert Szpera、Robert S. Paton、Véronique Gouverneur
DOI:10.1016/j.tet.2018.11.022
日期:2019.1
insertion reactions with tinhydrides affording the corresponding α-(trifluoromethyl)benzyl stannanes. This reactivity contrasts with that of diazo esters which predominantly afford CH2 reduction products in the presence of tinhydrides. The first example of asymmetric insertion into tinhydrides using diazo compounds is also described. In addition, this system extends to asymmetric germanium hydride and
The Mechanism of the Acid-catalysed Hydrolysis of 1-Aryl-2,2,2-trifluorodiazoethanes
作者:Georges Diderich
DOI:10.1002/hlca.19720550629
日期:1972.7.10
The rates of the acid-catalysedhydrolysis of a series of 1-aryl-2,2,2-trifluorodiazoethanes la-d have been measured in dioxan/water/HClO4. The results are well correlated with the Hammett equation when σp substituent constants are used (ϱH = −1.74 and ϱD = −1.75). Kinetic solvent isotope effects, about 2.1, and general acid catalysis indicate that proton transfer is rate-determining (A-SE2 mechanism)
已经在二恶烷/水/ HClO 4中测量了一系列1-芳基-2,2,2-三氟重氮乙烷1a-d的酸催化水解速率。当使用σp取代基常数时(results H = -1.74和ϱ D = -1.75),结果与哈米特方程具有很好的相关性。动力学溶剂的同位素效应(约为2.1)和一般的酸催化作用表明质子转移是决定速率的(AS E 2机理)。在高达1400atm的压力下也进行了速率测量。评估的激活体积,约-20 cm 3摩尔/摩尔表示在质子化的过渡状态下结合了至少一个水分子。在低水浓度下的速率测量表明,机理没有发生明显变化。