Regioselective Arylboration of 1,3-Butadiene

A method for the regioselective 1,2-arylboration of 1,3-butadiene, a feedstock chemical, is reported. The reactions result in the formation of products that can be easily elaborated to other structures. The mechanistic details of this process are also discussed.     

Regioselective Alkoxylation of 2,2,4-Trimethyl-1,3-pentanediol

An efficient procedure for the regioselective synthesis of secondary alcohol alkoxylates from 2,2,4-trimethyl-1,3-pentanediol (TMPD) is described. TMPD was reacted with propylene oxide followed by ethylene oxide in the presence of a catalytic amount of alkali metal hydroxide to form secondary alcohol alkoxylates. Instead of a mixture of compounds resulting from the reaction of TMPD and propylene oxide, the primary hydroxyl group of the TMPD reacted to form predominantly 2,2,4-trimethyl-3-hydroxypentylpropoxylate as the major product. On further ethoxylation the less hindered secondary hydroxyl group of the 2,2,4-trimethyl-3-hydroxypentylpropoxylate reacted predominantly. ¹³C NMR indicated that the secondary hydroxyl group (96.2 mol%) of TMPD remained unreacted during alkoxylation.     

1,3-Diketones as Active Ligands in the Nickel-Catalyzed Linear Oligomerization of Olefins

The novel complex (4-cyclooctene-l-yl)- bis(trifluoroacetamido) nickel oligomerizes ethene to olefins of about 85% linearity. Unusual high activities of 11500 mol ethene/mol nickel were obtained. Also higher α-olefins such as propene, butene or octene could be oligomerized yielding 70-80% linear dimers. By using (4-cyclooctene-1-yl)(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato) nickel activated by BF₃ the bulky olefin neohexene was converted selectively into dimers, which are linear, considering the C-C-linkage.     

Extended Scope and Understanding of Zinc-Dependent Alcohol Dehydrogenases for Reduction of Cyclic α-Diketones

Alcohol dehydrogenases (ADH) are important tools for generating chiral α-hydroxyketones. Previously, only the ADH of Thauera aromatica was known to convert cyclic α-diketones with appropriate preference. Here, we extend the spectrum of suitable enzymes by three alcohol dehydrogenases from Citrifermentans bemidjiense (CibADH), Deferrisoma camini (DecADH), and Thauera phenylacetica (ThpADH). Of these, DecADH is characterized by very high thermostability; CibADH and ThpADH convert α-halogenated cyclohexanones with increased activity. Otherwise, however, the substrate spectrum of all four ADHs is highly conserved. Structural considerations led to the conclusion that conversion of diketones requires not only the expansion of the active site into a large binding pocket, but also the circumferential modification of almost all amino acid residues that form the first shell of the binding pocket. The constellation appears to be overall highly specific for the relative positioning of the carbonyl functions and the size of the C-ring.     

Regioselective Organocatalytic Formation of Carbamates from Substituted Cyclic Carbonates

A highly regioselective catalytic approach has been developed towards carbamates derived from cyclic organic carbonates by reaction of the latter with amine reagents under organocatalytic control. For various combinations of carbonate and amine substrates, an organocatalyst (TBD: 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene) was used to increase the reaction kinetics while exerting excellent regioselective control. The current method is the first general approach towards the control over the regioselectivity of this reaction using a wide variety of easily accessed substituted organic carbonates.

     

Structural Basis of Cyclic 1,3-Diene Forming Acyl-Coenzyme A Dehydrogenases

The biologically important, FAD-containing acyl-coenzyme A (CoA) dehydrogenases (ACAD) usually catalyze the anti-1,2-elimination of a proton and a hydride of aliphatic CoA thioesters. Here, we report on the structure and function of an ACAD from anaerobic bacteria catalyzing the unprecedented 1,4-elimination at C3 and C6 of cyclohex-1-ene-1-carboxyl-CoA (Ch1CoA) to cyclohex-1,5-diene-1-carboxyl-CoA (Ch1,5CoA) and at C3 and C4 of the latter to benzoyl-CoA. Based on high-resolution Ch1CoA dehydrogenase crystal structures, the unorthodox reactivity is explained by the presence of a catalytic aspartate base (D91) at C3, and by eliminating the catalytic glutamate base at C1. Moreover, C6 of Ch1CoA and C4 of Ch1,5CoA are positioned towards FAD-N5 to favor the biologically relevant C3,C6- over the C3,C4-dehydrogenation activity. The C1,C2-dehydrogenation activity was regained by structure-inspired amino acid exchanges. The results provide the structural rationale for the extended catalytic repertoire of ACADs and offer previously unknown biocatalytic options for the synthesis of cyclic 1,3-diene building blocks.     

碘催化合成乙酰乙酸乙酯1，3-丙二醇缩醛

以单质碘为催化剂合成了乙酰乙酸乙酯 1,3丙二醇缩醛 [即 :2 -甲基 - 2 - (α -乙酸乙酯基 ) - 1,3-二氧六环 ]。考察了影响收率的因素 ,最佳优化条件为 :乙酰乙酸乙酯 :醇 :催化剂 :带水剂为 1mol :1.3mol :0 .0 5g :2 0 0mL ,反应在回流温度下进行 ,反应时间约 2 .5h。收率可达 92 .4 %。     

生物法合成1，3—丙二醇

1,3-丙二醇(PDO)的生产方法有化学法和微生物发酵法两种,1999年全球1,3-PDO产量达到8.1万t。微生物发酵法工艺与化学法相比条件温和、操作简便、副产物少、无环境污染,已成为各国研究的焦点。德国、法国、丹麦等欧洲国家开展了各种野生菌株将甘油转化为1,3-PDO的研究;DuPont公司与Genecor合作采用廉价的葡萄糖为底物,以基因工程菌为发酵微生物制备1,3-PDO;国内大连理工大学正在进行以玉米为原料经两步发酵生产1,3-PDO的研究。1,3-PDO是生产PTT的重要原料,为满足市场对PTT需求的增长,必须尽快解决1,3-PDO的工业化生产难题。     

微生物发酵法生产1,3-丙二醇

微生物发酵法生产1,3-丙二醇(PDO)以可再生资源——淀粉(糖)为原料,具有操作简便、反应条件相对温和、副产物少、污染少且容易处理等优点。目前,直接利用糖生产PDO以降低微生物发酵成本的方法主要有3种:以葡萄糖为辅助底物;采用混合菌或两步法发酵;基因工程菌的构建。清华大学化工系利用二元醇可与乙醛反应生成缩醛的原理研究了PDO的分离、提纯工艺,并在两步发酵法生产甘油专利技术的基础上,进一步开发了将甘油发酵第二步厌氧耗糖过程与PDO厌氧发酵耦合进行的新工艺。     

Chemistry of Substituted Quinolinones IV. Regioselective Nucleophilic Substitution of 1,3-Dichlorobenzo[f]quinoline

1,3-Dichlorobenzo[f]quinoline 2 was obtained from 1-hydroxybenzo[f]quinolin-3-one 1. Nucleophilic substitution, hydrolysis, hydrazinolysis and azidation reactions of compound 2 have been studied and found regioselective. Also, 1-aminobenzo[f]quinolinone 11 was obtained and used to prepare the benzoquinolinylthiourea derivative 12, naphthonaphthyridinedione 13, benzoquinolinylhydrazonoquinoline 15 and benzo[f]-quinolinyl enamine 17.     

Alkylations of Arylboronic Acids including Difluoroethylation/Trifluoroethylation via Nickel‐Catalyzed Suzuki Cross‐Coupling Reaction

An efficient alkylation method of functionalized alkyl halides under mild nickel‐catalyzed C(sp³) C(sp²) Suzuki cross‐coupling conditions is described. The features of this approach are excellent functional group compatibility, low cost nickel catalyst, and the use of a mild base. This is also the first successful example of the nickel‐catalyzed direct 2,2‐difluoroethylation or 2,2,2‐trifluoroethylation of aryl‐/heteroarylboronic acids.

     

A Regioselective Approach to Synthesize Indolyl Diketone Derivatives via Magnetic Polymeric Copper-Catalyst

Catalysis Letters - In the present paper, an efficient Cu-catalyzed regioselective acylation of indoles with phenylglyoxals was developed which is the first example of indolyl diketones synthesis...     

甘油和木糖共发酵生产1,3-丙二醇的研究

以克雷伯氏肺炎杆菌代谢甘油为研究对象,采用木糖作为发酵过程中的辅助底物与甘油共发酵生产1,3-丙二醇,以解决甘油单耗过大的问题,并研究了甘油和木糖共发酵过程中相关代谢物浓度的变化规律。实验表明:克雷伯氏肺炎杆菌可利用D-木糖经过磷酸戊糖途径为菌体代谢提供大量的还原力(NADPH和NADH),促进1,3-丙二醇的合成。与甘油单独发酵相比,以木糖作为辅助底物的微氧批次补料发酵中,1,3-丙二醇的质量浓度、甘油转化率及产量分别提高了10.58%,21.11%和10.98%。共发酵生产1,3-丙二醇在降低甘油到1,3-丙二醇单耗的同时,还可以促进副产物的生成,为克雷伯氏菌发酵多联产工艺提供了可能,从而较全面地降低甘油发酵生产1,3-丙二醇工艺的技术成本,具有一定的研究意义。     

Liquid-Liquid Extraction of Copper from Ammoniacal Solution with β-Diketones

Abstract

Some β-diketones such as LIX 51 (Henkel KGaA), Hostarex DK 16 (Hoechst AG), LIX 54 (Henkel KGaA), and MX 80A (Sigma Innovation, Sweden) were developed for technical applications (1) but only LIX 54 is commercially available. The use of LIX 54 to separate copper from ammoniacal etch solutions is described by patent applications (2–4) and an information paper of Henkel KGaA. The extraction of transition metals with LIX 54 was studied by Ramesh et al. (5). LIX 54 in a mixture with neutral donor ligands also proved suitable for the extraction of lanthanide elements (6). The active component of LIX 54 and MX 80A was recently identified as a mixture of isomeric l-phenyl-3-iso-heptyl-1,3-propanediones (7, 8). Analogous P-diketones are easily available.     

几种典型的选择性烷基化反应在精细化工中的应用

本文概述了三种典型的烷基化反应的特点及其研究进展,重点介绍了它们在精细化工中的重要性和应用情况.指出芳香族化合物、苯酚及吡嗪类化合物的选择性烷基化反应是精细化学品化学研究的重要方向,并分析了它们在选择性烷基化反应方面存在的问题和解决方法.     

The Synthesis of 1,2-Diarylpropane-1,3-Diols via the Ivanoff Reaction

Abstract

The synthesis of two β-1 lignol dimers, 1,2-bis-(4-hydroxy-3-methoxyphenyl)-i,3-propanediol (Via) and l-(3-ethoxy-4-hydroxyphenyl)-2-(4-hydroxy-3-methoxyphenyl)-1,3-propanediol (VIb) was performed using the Ivan off Reaction in the key synthetic step. The erythro forms of Via and b were isolated as crystalline solids in yields of approximately 15%, while the threo isomers were obtained as oils. The ratio of threo: erythro isomers was approximately 3:1.