2-bromo-3,3,3-trifluoropropene: A facile trifluoromethylacetylene anion synthon

The introduction of trifluoromethylacetylene units into organic compounds has been further studied and extended. The direct reaction of two equivalents of Lithium Diisopropylamide with 2-bromo-3,3.3-trifluoropropene gave lithium trifluoromethylacetylide, the anion of which was trapped in greater than 90% overall yield with a variety of electrophiles.     

Palladium-catalyzed cross-coupling of 6-bromo-2-methylbenzothiazole with arylzinc chlorides

Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2008–2009, November, 1993.     

Palladium-catalyzed cross-coupling of aryl electrophiles with dimethylalkynylaluminum reagents

[reaction: see text] Alkynyldimethylaluminum reagents are easily available from terminal alkynes and trimethylaluminum via a triethylamine-catalyzed metalation. These compounds can react with various aromatic and heterocyclic halides in the presence of palladium in a fast and efficient way. This catalyzed cross-coupling reaction provides a simple entry to numerous internal alkynes, using a readily available, inexpensive, and nontoxic metalating agent.     

Palladium-catalyzed cross-coupling reactions of carboxylic anhydrides with organozinc reagents

[reaction: see text] Negishi-type cross-coupling reaction was effected by employing organozincs and anhydrides or mixed anhydrides that formed in situ from sodium salts of the corresponding acids and ethyl chloroformate under the catalysis of palladium(0). A general method for preparing symmetrical/unsymmetrical ketones was developed.     

Palladium-catalyzed cross-coupling reaction of triorganoindium reagents with propargylic esters

[reaction: see text] Triorganoindium reagents (R(3)In) react with propargylic esters under palladium catalysis via an S(N)2' rearrangement to afford allenes in good yields and with high regioselectivity. The reaction proceeds smoothly at room temperature with a variety of R(3)In (aryl, alkenyl, alkynyl, and methyl). When chiral, nonracemic propargylic esters are employed, the reaction takes place with high anti-stereoselectivity providing allenes with high enantiomeric excess.     

Nitropyridines: X. Palladium-catalyzed cross-coupling of 2-bromo-5-nitropyridine with terminal acetylenes

Substituted 5-nitro-2-ethynylpyridines were synthesized by the Sonogashira reaction of 2-bromo-5-5-nitropyridine with terminal acetylenes. Desilylation, oxidative decarbonylation, and the retro-Favorskii reaction of the cross-coupling products of 2-bromo-5-nitropyridine with trimethylsilylacetylene, prop-2-ynyl alcohol, and 2-methylbut-3-yn-2-ol, respectively, gave 2-ethynyl-5-nitropyridine. The hydration of 2-ethynyl-5-nitropyridine and 5-nitro-2-(phenylethynyl)pyridine according to Kucherov afforded 2-acetyl-5-nitropyridine and 5-nitro-2-phenacylpyridine, respectively.     

Radical reaction of ethyl orthoacetate with 3,3,3-trifluoropropene

Summary The reaction of 3,3,3-trifluoropropene with ethyl orthoacetate leads to the formation of an acetate CH₃C(O)OCH(CH₃)CH₂CH₂CF₃ and a ketone CH₃C(O)CH₂CH(CF₃)CH₂CH₂CF₃. A reaction mechanism is proposed which involves rearrangement of the radicals CR₃C(OC₂H₅)₂OCH(CH₃) (CH₂CHCF₃) _n ^. with 1,7- and 1,5-migration of an H atom and stabilization by fragmentation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1583–1586, July, 1986.     

Radical telomerization of 3,3,3-trifluoropropene with 2-methyl-1,3-dioxolane

The telomerization of 3,3,3-trifluoropropene with 2-methyl-1,3-dioxolane gives predominantly cyclic telomers as shown by¹³C NMR and gas chromatography-mass spectrometry. This reaction is accompanied by the rearrangement of transient free radical intermediates via 1,5-H-migration.Institute of Heteroorganic Compounds, Russian Academy of Sciences, 117813 Moscow, Russia. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 12, pp. 2768–2772, December, 1992.     

Palladium-catalyzed cyclization and cross-coupling of acetylenic aryl triflates with organotin reagents

Acetylenic aryl triflates reacted readily with vinyltributyltin, allyltributyltin, 1-(trimethylsilyl)-2-(tributylstannyl)acetylene, and trimethylsilyltributyltin in the presence of a palladium catalyst to produce (Z)-indanylidene and (Z)-tetralinylidene substituted compounds, the stereospecificity of the reactions for the synthesis of these compounds being ≥98%.     

Radical reactions of ethyl orthoformate with 3,3,3-trifluoropropene

Conclusions The radical reaction of 3,3,3-trifluoropropene with ethyl orthoformate largely leads to the formation of the adduct, EtOC(O)OCH(Me)CH₂CH₂CF₃ due to rearrangement of the intermediate radicals with 1,5 hydrogen atom migration.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp.1418–1420, June, 1985.     

Preparative-scale synthesis of 3,3,3-trifluoropropene oxide

Bromination of 3,3,3-trifluoropropene in 20% oleum, followed by treatment with acetic acid furnishes 2-bromo-3,3,3-trifluoropropyl acetate in quantitative yield, which upon acid hydrolysis and cyclization with alkali affords 3,3,3-trifluoropropene oxide (TFPO) in 63% overall yield.     

Palladium-catalyzed cross-coupling reactions of in situ generated allylindium reagents with aryl halides

[reaction: see text] In situ generated allylindium reagents from the reaction of 1 equiv of indium with 1.5 equiv of allyl halides could be effective cross-coupling partners in palladium-catalyzed cross-coupling reactions to aryl halides. The best results were obtained with 2% Pd(2)dba(3)CHCl(3) and 16% Ph(3)P in the presence of 3 equiv of LiCl in DMF at 100 degrees C.     

Pd-catalyzed atom-economic couplings of triarylbismuth reagents with 2-bromo- and 2,6-dibromochromones and synthesis of medicinally important fisetin

Pd-catalyzed mono- and bis-arylation of chromones was demonstrated using triarylbismuths as threefold aryl transfer atom-economic reagents. This unprecedented study involving functionalized chromones afforded regio-selective mono-arylations leading to functionalized 2-arylchromones in good to high yields. Bis-arylation of 2,6-dibromochromones in one-pot operation furnished 2,6-diarylchromones in moderate to good yields. The present methodology was applied in the synthesis of naturally occurring and medicinally important fisetin molecule in high yield.     

一溴三氟丙烯灭火过程中HF的产生机理及生成量研究

卤烃灭火介质在灭火过程中, 受热分解产生的HF不仅对火灾现场的设备具有严重的腐蚀现象, 而且对灭火现场的人员存在严重的伤害, 故HF的生成量问题一直是卤烃灭火介质评价的重要性能指标之一. 一溴三氟丙烯(简称BTP)作为可降解卤烃的一种, 被认为是具有重大应用潜力的新一代“哈龙”替代技术, 然而, 目前对于BTP在灭火过程中HF的产生机理以及生成量预测, 尚缺乏深入的认识. 本工作首先应用量子化学从头算方法, 在B3LYP/6-311＋＋G(d,p)水平上, 对BTP在火场作用下的热分解动力学特性进行研究; 其次, 采用原位光谱诊断方法, 对BTP与火焰作用过程中HF的浓度变化进行实时在线测量, 全面评估不同工况下燃烧状况和腐蚀性气体的浓度变化情况; 再次, 以量化计算结果为基础, 通过理论分析和实验结果分析, 建立HF生成量的理论预测模型; 最后, 通过对各种实验工况下的实验结果与理论计算结果的比较, 验证HF理论计算模型的可靠性; 该论文的研究结果表明, 火焰温度以及BTP和火焰的接触时间, 为影响HF生产量的关键因素; 以量化计算结果为基础, 结合热分解动力学的理论, 构建出的HF生成量模型的计算结果和实验测量结果具有良好的一致性. 该论文的研究, 可以为优化BTP的系统设计, 减少腐蚀性气体的生成量和拓宽BTP的工程应用范围提供基础.     

Synthesis of aromatic polymers via palladium-catalyzed cross-coupling reactions with magnesium,zinc, and tin reagents: A comparison

Difunctional magnesium, zinc, and tin reagents M?C₆H₄?O?C₆H₄?M (M = MgBr, ZnCl, SnBu₃) in the presence of palladium or nickel catalysts undergo cross-coupling polymerizations with aromatic, heteroaromatic, benzylic, and allylic dihalides to give oligomeric and polymeric materials. Tin reagents lead to products of higher molecular weight than Mg and Zn reagents. The reaction is sensitive to the solvent and enhanced by magnesium halides. Increased reaction temperatures lead only to moderate increases in the degree of polymerization and are limited by catalyst decomposition above 200°C. The new poly(ether ketone) and poly(ether sulfone) type polymers prepared show high thermal stability. In contrast to conventional poly(ether sulfones)s, the biphenyl-based sulfone polymers reported here are crystalline. © 1992 John Wiley & Sons, Inc.     

Nickel-catalyzed N-heterocycle-directed cross-coupling of fluorinated arenes with organozinc reagents

Nickel-catalyzed N-heteroaromatics, such as pyridine, pyrazine or pyrimidine-directed cross-coupling of fluorinated arenes with organozinc reagents in the presence of sodium and PCy₃ was reported.