Reaction of the Dioxane Complex of Dichlorogermylene with Siloxanes

The major organogermanium compounds formed by reactions of the dioxane complex of dichlorogermylene with hexamethyldisiloxane, octamethyltrisiloxane, and hexamethyltricyclotrisiloxane are bis(trimethylsiloxy)dichlorogermane, 3,3-dichloro-1,1,1,5,5,7,7,7-octamethyl-3-germa-2,4,6-trioxa-1,5,7-trisilaheptane, and a cyclic germatetrasiloxane.     

The Suprising Variety of Products from Reactions of P-P Bonds with Dichlorogermylene

Abstract

Insertion of dichlorogermylene (from GcCl₂-dioxane) into the P-P bonds of tetraalkyldiphosphanes ((PRR)₂ (2a: R, R ? i-Pr; 2b: R? t-Bu, R?i-Pr; 2C; R, R, ?t-Bu) leads 10 dichlorobis(dialkylphosphanyl)germanes 3a-c. With 2a. the insertion remains incomplete: 38 exists in an equilibrium with an adduct of diphosphane 2a with GeCI₂, Subsequently 3b and 3c undergo a-climinarions to dialkylchlorophosphanes Sb and Sc and the dimeric phosphanylgermylenes (RR PGeGl)² 4b and 4c [1]. Similar to the above (but in absence of dioxane), reacting the richlorogcrmylphosphane i-Pr(t-Bu)PGeCL₃, 7c [2] with the related trichlorosilylphosphanc i-Pr(t-Bu)PSiCl₃ provided a mixture of SiCl₄, 1c, 3c, 5c and 7c, 3a and 3c have been trapped as inert molybdenum complexes (CO)₄ MO(μ-PRR)₂ GeGl₂ 6a and 6c from cquilibrilia conraining la/ 2a/ 3a and 3c/ 4c / 5c / 7c respectively.     

离子色谱法测定复杂氮硫化物

建立了复杂氮硫化物的离子色谱分析方法。在选定的色谱条件下能很好地分离多种高价及低价Ｎ－Ｓ化合物,尤其是能分析三价离子氨基三磺酸根。线性范围分别为：羟胺二磺酸根（０．０９８～６．９６０）×１０－４ｍｏｌ／Ｌ;氨基二磺酸根（０．１２５～１．５０９）×１０－４ｍｏｌ／Ｌ;氨基三磺酸根（０．３８０～３．０４６）×１０－４ｍｏｌ／Ｌ;羟胺一磺酸根（０．０２７～１．２４３）×１０－４ｍｏｌ／Ｌ;氨基一磺酸根（０．０１６～１．１６８）×１０－４ｍｏｌ／Ｌ。实验表明该法具有分析时间短、线性范围宽、灵敏和准确等优点     

通过金属有机化合物的β-消除切断化学键

金属有机化合物的β-原子或基团的消除反应是实现选择性切断非活性化学键(包括碳-氢键、碳-碳键和碳-杂原子键)的有效方法之一.介绍了近年来金属有机化合物的β-原子或基团消除反应研究进展以及该反应在有机合成中的应用.     

Reactions of Propargyl Compounds Containing a Cyclobutyl Group Induced by a Ruthenium Complex

Reactions of [Ru]Cl ([Ru]={Cp(PPh₃)₂Ru}; Cp=cyclopentadienyl) with three alkynyl compounds, 1 , 5 , and 8 , each containing a cyclobutyl group, are explored. For 1 , the reaction gives the vinylidene complex 2 , with a cyclobutylidene group, through dehydration at C_δH and C_γOH. With an additional methylene group, compound 5 reacts with [Ru]Cl to afford the cyclic oxacarbene complex 6 . The reaction proceeds via a vinylidene intermediate followed by an intramolecular cyclization reaction through nucleophilic addition of the hydroxy group onto C_α of the vinylidene ligand. Deprotonation of 2 with NaOMe produces the acetylide complex 3 and alkylations of 3 by allyl iodide, methyl iodide, and ethyl iodoacetate generate 4 a – c , respectively, each with a stable cyclobutyl group. Dehydration of 1 is catalyzed by the cationic ruthenium acetonitrile complex at 70 °C to form the 1,3‐enyne 7 . The epoxidation reaction of the double bond of 7 yields oxirane 8 . Ring expansion of the cyclobutyl group of 8 is readily induced by the acidic salt NH₄PF₆ to afford the 2‐ethynyl‐substituted cyclopentanone 9 . The same ring expansion is also seen in the reaction of [Ru]Cl with 8 in CH₂Cl₂, affording the vinylidene complex 10 , which can also be obtained from 9 and [Ru]Cl. However, in MeOH, the same reaction of [Ru]Cl with 8 affords the bicyclic oxacarbene complex 12 a through an additional cyclization reaction. Transformation of 10 into 12 a is readily achieved in MeOH/HBF₄, but, in MeOH alone, acetylide complex 11 is produced from 10 . In the absence of MeOH, cyclization of 10 , induced by HBF₄, is followed by fluorination to afford complex 13 . Crystal structures of 6 and 12 a ′ were determined by single‐crystal diffraction analysis.     

咔唑桥连NCN齿形钯配合物催化的唑类C-H键直接芳基化反应

基于咔唑的强给电子能力合成了一种对空气稳定的齿形钯配合物催化剂(C1~C6).这种钯催化剂可高效催化唑类和溴代芳烃的直接芳基化反应,在空气条件下,碳酸钾为碱,无需其他添加剂,即取得了较好的催化活性与底物普适性.在相对温和的条件和催化剂用量为0.5mol%时,即可实现噻唑与溴代芳烃直接芳基化反应顺利进行.值得一提的是,这是目前以KOAc为碱的反应体系中,反应活性最高的催化体系.     

Mannich Reaction as a Convenient Route to New Macrocyclic Compounds Containing an Uracil Fragment

Mannich reaction of 1,3-bis[4-(2-mercaptomethylphenoxy)butyl]-6-methyl-1,2,3,4-tetrahydropyrimidine-2,4-dione, formaldehyde, and N-benzylamine afforded a 24-membered macrocyclic compound containing an uracil fragment, 1,3-(11-benzyl-6,7:15,16-dibenzo-5,17-dioxa-9,13-dithia-11-aza-6,15-heneicosadiene-1,21-diyl)-6-methyl-1,2,3,4-tetrahydropyrimidine-2,4-dione.     

铜催化的芳环C—H键直接芳基化反应研究进展

铜催化的芳环C—H键直接芳基化反应已成为一种合成联芳烃化合物的重要手段,近年来一直是有机化学和催化化学的研究热点和难点之一.按照参与反应的底物或成键模式的不同对近年来铜催化的芳环C—H键直接芳基化反应的研究进展进行了综述.     

Five-Membered 2,3-Dioxo Heterocycles: XLVII. Reaction of 5-Aryl-4-phenyl-2,3-dihydrofuran-2,3-diones with Compounds Containing C = N and C≡N Bonds

Thermal decarbonylation of 5-aryl-4-phenyl-2,3-dihydrofuran-2,3-diones gives rise to intermediate aroyl(phenyl)ketenes which react with nonactivated Schiff bases, N,N'-dicyclohexylcarbodiimide, and p-di-methylaminobenzonitrile according to the [4 + 2]-cycloaddition pattern with formation of 6-aryl-5-phenyl-4H-1,3-oxazin-4-ones. Reactions of 5-aryl-4-phenyl-2,3-dihydrofuran-2,3-diones with activated Schiff bases at a temperature below the thermolysis temperature lead to 4-aroyl-4-phenyltetrahydropyrrole-2,3-diones.     

生物催化C-H键不对称羟基化反应的研究进展

C-H键的不对称羟基化反应是有机合成领域的研究热点和难点之一。生物催化的不对称羟基化反应具有较好的区域选择性和立体选择性,可作为化学催化C-H键不对称羟基化方法的有力补充,而目前关于生物催化的C-H键不对称羟基化反应的评论文章鲜有报道。本文结合本课题组的研究基础,根据底物类型,综述了生物催化链烷烃、环烷烃、芳香烷烃、烯烃、杂环化合物和天然化合物的不对称羟基化反应的进展,参考文献44篇。     

过渡金属催化的惰性碳氢键卤化反应研究进展

卤化反应是有机化学中最重要的反应之一,近年来,过渡金属催化的碳氢键卤化反应已经成为合成有机卤化物的重要方法.本文综述了过渡金属催化的惰性碳氢键卤化的研究进展,按照不同的过渡金属(钯、铜、铑、钌、钴)对底物范围和反应机理等进行详细的探讨,并对该领域的局限性和未来发展进行了总结和展望.     

Anionic Reagents with Silicon‐Containing Double Bonds

E?Si transfer : Anionic compounds capable of transferring a silicon‐containing double bond are reviewed (see figure), particularly reagents with Si?Si moieties (Tip=2,4,6‐iPr₃C₆H₂, M=Li, Na, K) and their applications towards main‐group and transition‐metal electrophiles, as well as their reactivity towards organic compounds. A few recently reported derivatives with Si?C (Ad=1‐adamantyl) and Si?P moieties are included for completeness.

     

可见光催化的氮自由基导向远程sp3碳氢官能团化反应

远程sp ³碳氢键官能团化反应近年来引起广泛关注, 可见光催化的氮自由基导向选择性官能化这一技术的出现使得该领域的发展取得了可喜的进展. 该策略以氮自由基介导的Hoffman-L?ffler-Freytag (HLF)反应为基础, 通过在可见光照射下激发态自由基的生成和1,5-攫取氢原子(1,5-HAT)过程, 利用反应过程中形成的自由基中间体, 实现对远程sp ³碳-氢键的修饰. 本综述就可见光催化的氮自由基导向远程碳氢官能团化反应近年来取得的进展进行简要总结.