Direct Difluoromethylenation of Carbonyl Compounds by Using TMSCF<sub>3</sub>: The Right Conditions
作者:Sankarganesh Krishnamoorthy、Jotheeswari Kothandaraman、Jacqueline Saldana、G. K. Surya Prakash
DOI:10.1002/ejoc.201601038
日期:2016.10
A deoxygenative difluoromethylenation of carbonylcompounds has been developed by using readily available, inexpensive trifluoromethyltrimethylsilane, LiI, and PPh3. The presence of the Li+ ion prevents the unproductive exhaustion of trifluoromethyltrimethylsilane (TMSCF3) by keeping the soluble free fluoride concentration in the reaction medium under control. The strategy of combining solvents to
Reaction of the Ruppert–Prakash reagent (Me3SiCF3) with aromatic aldehydes in the presence of triphenylphosphine, lithium iodide and lithium tetrafluoroborate selectively furnishes gem-difluorinated phosphonium salts. Simple alkaline hydrolysis of these salts results in difluoromethylated products. Thus, one-pot nucleophilic difluoromethylation of aromatic aldehydes using Me3SiCF3 has been accomplished
A key intermediate, difluoromethylene phosphobetaine, in the Wittig reaction of ClCF2CO2Na–Ph3P with aldehydes was synthesized and characterized, which confirmed the reaction mechanism. The decarboxylation of this stable intermediate was a convenient approach for Wittig difluroolefination. Its reactivity could be adjusted by the modification of the substituent on the phosphorus.
Difluoromethyl 2-Pyridyl Sulfone: A New <i>gem-</i>Difluoroolefination Reagent for Aldehydes and Ketones
作者:Yanchuan Zhao、Weizhou Huang、Lingui Zhu、Jinbo Hu
DOI:10.1021/ol100090r
日期:2010.4.2
Difluoromethyl2-pyridylsulfone, a previously unknown compound, was found to act as a novel and efficient gem-difluoroolefination reagent for both aldehydes and ketones. It was found that the fluorinated sulfinate intermediate in the reaction is relatively stable, which can be observed by 19F NMR and trapped with CH3I.
发现二氟甲基2-吡啶基砜(一种以前未知的化合物)可同时作为醛和酮的新型高效二氟烯烃聚合试剂。发现反应中的氟化亚磺酸盐中间体相对稳定,这可以通过19 F NMR观察到并被CH 3 I捕获。
Photocatalytic alkene reduction by a B<sub>12</sub>–TiO<sub>2</sub> hybrid catalyst coupled with C–F bond cleavage for gem-difluoroolefin synthesis
Photocatalytic syntheses of gem-difluoroolefins were performed using the B12–TiO2 hybrid catalyst during the CC bondreduction of α-trifluoromethyl styrenes with C–F bondcleavage at room temperature under nitrogen. The gem-difluoroolefins were used as synthetic precursors for fluorinated cyclopropanes.