Oxidation of Primary Aliphatic and Aromatic Aldehydes with Difluoro(aryl)-λ3-bromane
摘要:
Oxidation of primary aliphatic aldehydes with p-trifluoromethylphenyl(difluoro)-lambda(3)-bromane in dichloromethane at 0 degrees C afforded acid fluorides selectively In good yields, while that of aromatic aldehydes In chloroform at room temperature produced aryl difluoromethyl ethers. A larger migratory aptitude of aryl groups compared to primary alkyl groups during a 1,2-shift from carbon to an electron-deficient oxygen atom in bromane(III) Criegee-type intermediates will result in these differences in the reaction courses.
Diethyl bromodifluoromethylphosphonate: a highly efficient and environmentally benign difluorocarbene precursor
作者:Yossi Zafrani、Gali Sod-Moriah、Yoffi Segall
DOI:10.1016/j.tet.2009.04.082
日期:2009.7
thiophenols, using diethyl bromodifluoromethylphosphonate (1) as a difluorocarbene precursor, is described. This commercially available phosphonate was found to undergo an extremely facile P–C bond cleavage on basichydrolysis (−78 °C to rt), presumably leading to the bromodifluoromethyl anion, which subsequently converts to a difluorocarbene intermediate. The latter is trapped by phenolates 2 or thiophenolates
compounds containing the difluoromethyl group, as it is considered a lipophilic hydrogenbonddonor that may act as a bioisostere of hydroxyl, thiol, or amine groups. A series of difluoromethyl anisoles and thioanisoles was prepared and their druglike properties, hydrogenbonding, and lipophilicity were studied. The hydrogenbond acidity parameters A (0.085–0.126) were determined using Abraham’s solute 1H
人们对含二氟甲基的有机化合物越来越感兴趣,因为它被认为是亲脂性的氢键供体,可以作为羟基,巯基或胺基的生物等排体。制备了一系列的二氟甲基茴香醚和硫代苯甲醚,并研究了它们的类药物性质,氢键和亲脂性。氢键酸度参数A(0.085–0.126)使用亚伯拉罕的溶质1 H NMR分析确定。发现二氟甲基基团以与硫酚,苯胺和胺基团相似的规模充当氢键供体,但不如羟基基团那样。尽管二氟被认为是亲油性增强组,实验Δlog的范围 P(水-辛醇)值日志( P(XCF 2 H)– log P(XCH 3))范围从-0.1到+0.4。对于这两个参数,在测量值和Hammettσ常数之间发现线性相关。这些结果可能有助于合理设计含有二氟甲基部分的药物。
Three step procedure for the preparation of aromatic and aliphatic difluoromethyl ethers from phenols and alcohols using a chlorine/fluorine exchange methodology
作者:William R. Dolbier、Fei Wang、Xiaojun Tang、Charles S. Thomoson、Linhua Wang
DOI:10.1016/j.jfluchem.2014.01.018
日期:2014.4
Difluoromethyl ethers are prepared from phenols in three steps via their respective formate ester derivatives. The formates are first converted to dichloromethyl ethers by treatment with PCl5. These ethers are then induced to undergo chlorine/fluorine exchange to form the respective difluoromethyl ethers. The chlorine/fluorine exchange is carried out by either a room temperature, solvolytic process using THF-5HF
Redox‐Neutral TEMPO Catalysis: Direct Radical (Hetero)Aryl C−H Di‐ and Trifluoromethoxylation
作者:Johnny W. Lee、Sanghyun Lim、Daniel N. Maienshein、Peng Liu、Ming‐Yu Ngai
DOI:10.1002/anie.202009490
日期:2020.11.23
Applications of TEMPO. catalysis for the development of redox‐neutral transformations are rare. Reported here is the first TEMPO.‐catalyzed, redox‐neutralC−Hdi‐ and trifluoromethoxylation of (hetero)arenes. The reaction exhibits a broad substrate scope, has high functional‐group tolerance, and can be employed for the late‐stage functionalization of complex druglike molecules. Kinetic measurements
TEMPO 的应用。氧化还原中性转化发展的催化作用很少见。这里报道的是第一个TEMPO 。(杂)芳烃的催化氧化还原中性 C−H 二氟甲氧基化和三氟甲氧基化。该反应表现出广泛的底物范围,具有较高的官能团耐受性,可用于复杂药物分子的后期功能化。动力学测量、催化中间体的分离和重新研究、UV/Vis 研究和 DFT 计算支持了所提出的氧化 TEMPO 。/TEMPO +氧化还原催化循环。机理研究还表明Li 2 CO 3在防止催化剂失活方面发挥着重要作用。这些发现将为通过氧化还原中性 TEMPO 设计和开发新型反应提供新的见解。催化。
Deoxygenative <i>gem</i>-difluoroolefination of carbonyl compounds with (chlorodifluoromethyl)trimethylsilane and triphenylphosphine
作者:Fei Wang、Lingchun Li、Chuanfa Ni、Jinbo Hu
DOI:10.3762/bjoc.10.32
日期:——
phosphonium ylide represents one of the most straightforward methods. RESULTS: The combination of (chlorodifluoromethyl)trimethylsilane (TMSCF2Cl) and triphenylphosphine (PPh3) can be used for the synthesis of gem-difluoroolefins from carbonyl compounds. Comparative experiments demonstrate that TMSCF2Cl is superior to (bromodifluoromethyl)trimethylsilane (TMSCF2Br) and (trifluoromethyl)trimethylsilane