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41.
Dihalocarbenes generated under phase transfer conditions add to cis and trans vinylic selenides to give the corresponding 1,1-dihalo-2-selenocyciopropanes with retention of configuration. 相似文献
42.
To gain access to prenylated hexahydroxanthenes, tandem cascade cyclization–electrophilic aromatic substitution reactions have been studied on substrates bearing allylic and propargylic substituents. Both BF3·OEt2 and TMSOTf can be used to initiate this reaction sequence, resulting in different ratios of the C-2 and C-6 substitution products. Even though allylic transposition is observed in some cases, the results of a crossover experiment are consistent with an intramolecular reaction sequence. Taken together, these studies now allow preparation of either the C-2 or C-6 prenylated hexahydroxanthene products. 相似文献
43.
《Tetrahedron》2014,70(51):9601-9614
3,6-Bis-(2-indolyl)dibenzofurans 1,2, and carbazoles 3–6 underwent a range of electrophilic substitution reactions to produce formyl indoles 7–12, biindolyls 24–28 and 33–34, glyoxylamides 40–42, and amides 48. 相似文献
44.
《Comptes Rendus Chimie》2014,17(5):443-449
Different strategies for the synthesis of 2′-hydroxy-4′-methylsulfonylacetophenone are reported in the present paper. This compound is considered as a key synthon for the synthesis of new flavonoid derivatives designed as potential cyclooxygenase-2 inhibitors. The retrosynthetic approach via 3′-methylsulfonylacetophenone, which included three synthetic pathways, did not allow us to obtain the expected compound. However, a synthesis from 3-mercaptophenol led to the desired acetophenone in three steps: thiophenol methylation, Friedel–Crafts acetylation and oxidation of the sulphide to the corresponding sulfone. The desired compound, 2′-hydroxy-4′-methylsulfonylacetophenone, will be used as a synthon for the preparation of novel flavonoid derivatives, such as 2′-hydroxychalcones, flavanones, flavones, and flavonols. 相似文献
45.
Yuji Kikukawa Kensuke Seto Daiki Watanabe Hiromasa Kitajima Misaki Katayama Shohei Yamashita Yasuhiro Inada Yoshihito Hayashi 《Angewandte Chemie (International ed. in English)》2020,59(34):14399-14403
Dodecavanadate, [V12O32]4? (V12), possesses a 4.4 Å cavity entrance, and the cavity shows unique electrophilicity. Owing to the high polarizability, Br2 was inserted into V12, inducing the inversion of one of the VO5 square pyramids to form [V12O32(Br2)]4? (V12(Br2)). The inserted Br2 molecule was polarized and showed a peak at 185 cm?1 in the IR spectrum. The reaction of V12(Br2) and toluene yielded bromination of toluene at the ring, showing the electrophilicity of the inserted Br2 molecule. Compound V12(Br2) also reacted with propane, n‐butane, and n‐pentane to give brominated alkanes. Bromination with V12(Br2) showed high selectivity for 3‐bromopentane (64 %) among the monobromopentane products and preferred threo isomer among 2‐,3‐dibromobutane and 2,3‐dibromopenane. The unique inorganic cavity traps Br2 leading the polarization of the diatomic molecule. Owing to its new reaction field, the trapped Br2 shows selective functionalization of alkanes. 相似文献
46.
YinQing Yao KaiChun Zhao YiYing Zhuang XiaoChao Chen Prof.Dr. Yong Lu Prof.Dr. Ye Liu 《ChemistryOpen》2022,11(4)
The one‐pot synthesis of 2,5‐furandicarboxylic acid from 2‐furoic acid with a yield of 57 % was achieved for the first time using a Pd‐catalyzed bromination‐hydroxycarbonylation tandem reaction in HOAc‐NaOAc buffer. This synthetic protocol shows major improvements compared to previously reported methods, such as using biomass‐based 2‐furoic acid as low‐cost raw material, one‐pot synthesis without isolation of intermediate products, and no need for an acidification procedure. Experiments indicate that the involved Xantphos‐modified Pd‐catalyst and the buffer solution play significant promoting roles for each individual reaction whereas Br2 (as the brominating reagent) had a negative effect on the second hydroxycarbonylation step, while CO was deleterious for the first bromination step. Hence, in this practical one‐pot synthesis, Br2 should be consumed in the first bromination step as fully as possible, and CO is introduced after the first bromination step has been completed. 相似文献
47.
合成了一系列2-羟基-4-三氟甲基苯甲酸(h2tba)-铜配合物:[Cu(htba)2(pz)2](1),[Cu(htba)(2,2''-bipy)](htba)(2)和[Cu(htba)2(4,4''-bipy)](3)(h2tba=2-羟基-4-三氟甲基苯甲酸,pz=吡唑,2,2''-bipy=2,2''-联吡啶,4,4''-bipy=4,4''-联吡啶),并且通过元素分析、红外光谱、紫外光谱、粉末X射线衍射、单晶X射线衍射和热重分析方法对配合物结构进行了表征。这些配合物能够在过氧化氢和溴化物存在的条件下催化苯酚红溴化,并且展示出了较高的催化溴化活性。 相似文献
48.
为了研究α-四芳氧基取代酞菁在溴化反应中溴原子的取代位置问题,本文合成了1,8,15,22-四(4-甲基苯氧基)酞菁钯(Pc~1)、1,8,15,22-四(2,6-二溴-4-甲基苯氧基)酞菁钯(Pc~2)、1,8,15,22-四(2,4-二特丁基苯氧基)酞菁钯(Pc~3)和1,8,15,22-四(2,4-二特丁基苯氧基)酞菁铜(Pc~4),并对它们分别进行了相同条件下的溴化,得到相应的溴化产物Pc~5、Pc~6、Pc~7和Pc~8.综合对比研究酞菁Pc~1-4及其溴化产物Pc~5-8的最大吸收波长,推测酞菁溴化反应发生在酞菁大共轭体系的苯环上,而不是芳氧取代基的苯环上,并从电子结构的角度简要的说明了原因. 相似文献
49.
Jie Ju Yu Jin Li Jian Rong Gao Jian Hong Jia Liang Han Wei Jian Sheng Yi Xia Jia 《中国化学快报》2011,22(4):382-384
An aqueous solution of hydrogen peroxide and hydrogen bromide illuminated by a 60 W incandescent light bulb serves as a source of bromine radicals.Various substituted toluenes(NO2,Cl,Br,H,CH3) were high selectively brominated at the benzyl position for monobromination in CH2C12 at ice water with catalyst free.This simple but effective bromination of toluene derivatives with an aqueous H2O2-HBr system is characterized with the use of inexpensive reagents and a lower impact on the environment, which make it a good alternative to the existing bromination methods. 相似文献
50.
Thomas M. Klapötke 《Journal of fluorine chemistry》2006,127(6):679-687
The experimental and theoretical chemistry of nitrogen-fluorine compounds is an area that has seen considerable renaissance over the past decade. This review is not exhaustive in scope but rather focuses on and highlights certain aspects in this field. In particular (but not exclusively), the chemistry of binary N-F species is discussed. 相似文献