(2S)-(+)-2-溴-1-(6'-甲氧基-2'-萘基)丙-1-酮的不对称合成

以(2R,3R)-酒石酸二甲酯为手性辅助剂,6-甲氧基-2-丙酰基萘经缩酮化、溴化铜不对称溴化、水解等反应合成了(2S)-2-溴-1-(6'-甲氧基-2'-萘基)丙-1-酮。总收率94%。     

Synthesis of 2-benzoylethynylpyrroles by cross coupling of 2-arylpyrroles with 1-benzoyl-2-bromoacetylene over aluminum oxide

Cross coupling of 2-arylpyrrole with benzoylbromoacetylene over aluminum oxide at room temperature gave 45–94% of 2-(benzoylethynyl)-5-arylpyrroles. Intermediate 2-(2-benzoyl-1-bromoethenyl)-5-arylpyrroles were isolated in up to 19% yield. The reaction was accompanied by formation of less than 5% of adducts of the initial pyrroles with the cross-coupling products, 2-benzoyl-1,1-bis(5-arylpyrrol-2-yl)ethenes.     

铱催化 3-羟甲基-2H-苯并吡喃类化合物的不对称氢化

从(1R,2S)-环己烷吡啶醇出发,合成了具有不同轴手性的反式环己烷骨架铱络合物,并将其应用于3-羟甲基-2H-苯并吡喃的不对称氢化中.结果表明,当以Ir-8为催化剂,二氯甲烷为溶剂,氢气压力5MPa,室温反应16h时,可以取得极好的反应活性,产物最高对映选择性可达94%.     

Enantioselective intramolecular [2 + 2]-photocycloaddition reactions of 4-substituted quinolones catalyzed by a chiral sensitizer with a hydrogen-bonding motif

Six 2-quinolones, which bear a terminal alkene linked by a three- or four-membered tether to carbon atom C4 of the quinolone, were synthesized and subjected to an intramolecular [2 + 2]-photocycloaddition. The reaction delivered the respective products in high yields (78-99%) and with good regioselectivity in favor of the straight isomer. If conducted in the presence of a chiral hydrogen-bonding template (2.5 equiv) at low temperature in toluene as the solvent, the reaction proceeded enantioselectively (83-94% ee). An organocatalytic reaction was achieved when employing a chiral hydrogen-bonding template with an attached sensitizing unit (benzophenone or xanthone). The xanthone-based organocatalyst proved to be superior as compared to the respective benzophenone. Closer inspection revealed that the reaction of 4-(pent-4-enyloxy)quinolone leading to a six-membered ring, annelated to the cyclobutane, was less enantioselective (up to 41% ee with 30 mol % catalyst) than the reaction of 4-(but-3-enyloxy)quinolone leading to a five-membered ring (90% ee with 5 mol % and 94% ee with 20 mol % catalyst). Photophysical data (emission spectra, laser flash photolysis experiments) proved that the latter photocycloaddition was significantly faster, supporting the idea that the dissociation of the substrate from the catalyst prior to the photocycloaddition is responsible for the decreased enantioselectivity. Under optimized conditions, employing 10 mol % of the xanthone-based organocatalyst at -25 °C in trifluorotoluene as the solvent, three of the other four substrates gave the intramolecular [2 + 2]-photocycloaddition products with high enantioselectivities (72-87% ee). In all catalyzed reactions, the yields based on conversion were moderate to good (40-93%).     

Application of the "Fries Like" Rearrangement Using ZnCl 2 for the Synthesis of 6-Acyl-2(3H)-benzothiazolones

In this work we report another method of acylation on the 6-position of the 2(3H)-benzothiazolone ring with Fries-like rearrangement catalyzed by zinc chloride instead of aluminium chloride and 3-acyl-2(3H)-benzothiazolones derivatives as starting materials. This method is advantagous in regard to other acylation methods as it requires only three equivalents of ZnCl 2 to produce 6-acyl-derivatives with yields of 82-94%.     

Kishner's reduction of 2-furylhydrazone gives 2-methylene-2,3-dihydrofuran, a highly reactive ene in the ene reaction

[reaction: see text] The Kishner reduction of 2-furylhydrazone gives 2-methylene-2,3-dihydrofuran as the major abnormal reduction product. 2-Methylene-2,3-dihydrofuran is an excellent ene in the carbonyl-ene reaction, reacting with a variety of aldehydes. Most notable was the asymmetric carbonyl-ene reaction of 2-methylene-2,3-dihydrofuran and decanal using Ti(OCH(CH3)2)4/(S)-BINOL to give the corresponding alcohol in 66% yield and 94% ee. The reaction of 2-methylene-2,3-dihydrofuran with 2 equiv of 1,4-benzoquinone unexpectedly gave a monoalkylated 1,4-hydroquinone/1,4-benzoquinone electron donor-acceptor complex.     

P(RNCH(2)CH(2))(3)N-catalyzed 1,2-addition reactions of activated allylic synthons.

Activated allylic compounds of the type RCH:CHCH(2)Z (Z = CN, CO(2)Me) react efficiently with aromatic aldehydes in the presence of 20-40 mol % of P(R'NCH(2)CH(2))(3)N at -94 to -63 degrees C. Both R = H and R = Me lead exclusively to alpha-addition products. When R = H and Z = CN, an allylic transposition occurs to afford a Baylis-Hillman product as the only product.     

钴联吡啶配合物在硅电极表面高效光电催化二氧化碳还原反应（英文）

光驱动二氧化碳还原实现可再生能源转化近年来引起普遍关注.利用小分子金属配合物电催化剂和吸光半导体材料构建的光电催化体系兼具电催化剂的高选择性和光电极的高光电转化效率等优点,在能源催化领域的应用日益广泛.已有将贵金属配合物催化剂用于光电催化二氧化碳还原的研究报道,但催化剂成本较高且制备方法不简便,在规模化实际应用中受到局限.基于早期的研究报道,我们发现非贵金属多联吡啶铁钴镍配合物在乙腈电解质中能高选择性电催化还原二氧化碳.结合半导体材料的特异性电荷分离性能从而将光能高效转化为电能驱动催化反应进行,我们选择廉价且易于制备的多联吡啶钴配合物催化剂,利用半导体硅晶片光电极,实现了均相体系二氧化碳的高效光电催化还原.我们采用电化学循环伏安法和恒电位电解法分别研究了催化剂在干燥和加水电解质环境中的催化还原行为,并且进一步研究了微量质子源的加入对半导体界面催化过程的影响,从而提出一种能改善半导体光电催化体系选择性的新方法.首先我们构建了电化学三电极体系,研究了在暗环境下三联吡啶钴和二联吡啶钴这两种配合物催化还原二氧化碳的电流密度和电解产物分布情况.由循环伏安曲线发现,这两种配合物都有两组催化还原峰,第二个基于吡啶配体还原的峰具有明显的催化特性.少量水的加入能进一步增加催化电流强度,而三联吡啶钴配合物的催化增强效果更加显著.在变扫速条件下将电流密度对扫速平方根进行归一化处理,发现无论在干燥环境还是少量加水环境下,两种催化剂的归一化电流密度均随扫速降低而明显增强,证明了催化剂具有电催化特性.推测水的催化增强作用可能与质子化电催化过程活性中间体有关.恒电位电解结果说明电催化产物以一氧化碳为主.基于上述研究,我们构建了光电化学三电极体系,以单晶硅片为工作电极,研究了在光照环境下这两种配合物催化还原二氧化碳的电流密度和电解产物分布情况.研究发现,催化剂对二氧化碳仍具有催化活性,光电压为400 m V.不同于硅线电极加水导致产氢,改用少量甲醇做质子源后,光电流强度进一步增强,竞争性产氢受到了抑制,从而使一氧化碳的法拉第效率得到显著提高,分别优化为94%和83%,并且光电流在14h内保持稳定.推测甲醇质子源的催化增强作用可能是与改变光电极液接界面传质动力学过程有关.     

Catalytic enantioselective desymmetrization of meso-glutaric anhydrides using a stable Ni2-Schiff base catalyst

We describe the desymmetrization of meso-glutaric anhydrides to chiral hemiesters using a bench-stable homodinuclear Ni(2)-(Schiff base) complex as the catalyst in good to excellent yield (up to 99%) and enantioselectivity (up to 94%). Using the opposite enantiomer of the catalyst, we obtained the same yield and enantioselectivity with the opposite configuration, thereby gaining access to both hemiester enantiomers.     

微波辅助氢氧化钾催化合成2-(4-羟基苯基)六氟异丙醇

微波辐射下,在水溶液中以KOH催化苯酚与六氟丙酮三水合物（HFA·3H2O）的缩合反应,制备了2-(4-羟-基苯基)六氟异丙醇的异构体混合物;目标产物结构经IR、1H NMR和MS确认。 结果表明,与传统加热法相比,微波辐射法可明显缩短反应时间。 在n(苯酚)∶n(HFA·3H2O)∶n(KOH)=3.0∶1.0∶0.3及微波功率为300 W条件下,反应时间可由常规加热法的35 h缩短至6 h,总收率由87%提高到90%,目标物产物选择性为94%。     

三氟甲基磺酸锌催化选择性合成2-苄基-4-氯苯酚

在温和条件下,Zn(OTf)2能有效催化氯化苄对对氯苯酚的C-苄基化反应,选择性合成杀菌剂2-苄基-4-氯苯酚（BCP）,合成的优化条件为n(对氯苯酚):n(氯化苄)=1.2:1,催化剂Zn(OTf)2对氯化苄摩尔分数为5%,60 ℃下反应6 h,用硝基甲烷为溶剂,氯化苄转化率和产物BCP的产率分别＞99%和94%。     

3-氯-2-烃基四氢吡喃的镁开环反应

研究了用镁对3-氯-2-烃基四氢吡喃(1)的开环反应,制得一系列5-烃基-4-戊烯-1-醇(2),上述反应产率高,立体选择性强,无论顺式或反式的(1)开环时都得到反式(2).     

Synthesis of 2-oxazolines via boron esters of N-(2-hydroxyethyl) amides

A new, convenient, one-pot process is presented for the synthesis of 2-oxazolines in high yields (75-94%) via boron esters of N-(2-hydroxyethyl) amides. The procedure involves thermolysis of the boron esters at 240-260 °C, in the presence of solid CaO as an acid scavenger and allows the preparation of oxazolines from hydroxyethyl amides of aliphatic and aromatic monocarboxylic acids.     

Highly enantioselective sequential hydrogenation of ethyl 2-oxo-4-arylbut-3-enoate to ethyl 2-hydroxy-4-arylbutyrate

The hydrogenation of (E)-ethyl 2-oxo-4-arylbut-3-enoate with [NH2Me2](+)[{RuCl [(S)-SunPhos]}2(mu-Cl3)] gave ethyl 2-hydroxy-4-arylbutyrate with 94-96% ee. Further investigation has proved that the hydrogenation proceeded via a sequential hydrogenation of CO and CC bonds, which is sensitive to the reaction temperature. Hydrolysis of ethyl 2-hydroxy-4-phenylbutyrate (ee 93%) provided the 2-hydroxy-4-phenylbutyric acid with 81% yield at 99% ee after a single recrystallization from 1,2-dichloroethylene.     

Highly enantioselective hydrogenation of new 2-functionalized quinoline derivatives

The asymmetric hydrogenation of a new series of 2-functionalized quinolines has been developed in the presence of in situ generated catalysts obtained from [Ir(cod)Cl]₂/(R)-bisphosphine/I₂ combinations. The enantioselectivity levels were as high as 84-94% ee for the synthesis of 1,2,3,4-tetrahydroquinolines.     

Asymmetric intramolecular [2 + 2] photocycloadditions: alpha- and beta-hydroxy acids as chiral tether groups

Chiral alpha- and beta-hydroxy acids such as (S)-lactic acid, (S)-phenyllactic acid, (S)-mandelic acid, or (3R)-3-hydroxybutyric acid have been used as tether groups for intramolecular and diastereoselective [2 + 2] photocycloaddition of 3-oxocyclohexene carboxylic acid derivatives. Total regiocontrol toward the straight adduct and high diastereoselectivities (up to 94%) were observed in the case of butenyl lactate 11. After separation of the two diastereoisomers, cleavage of the chiral tether under basic conditions afforded cyclobutane lactones in good yield and enantiomeric pure form. An X-ray structure has been recorded that confirmed the relative and absolute configuration of the three contiguous stereogenic centers assigned according to CD spectra.     

Regiospecific [2+2] cycloadditions of electron-poor acetylenes to (Z)-2-acylamino-3-dimethylaminopropenoates: synthesis of highly functionalised buta-1,3-dienes

Microwave-assisted [2+2] cycloaddition reactions of 2-amino-3-dimethylaminopropenoates with acetylenecarboxylates furnished highly functionalised 1-amino-4-(dimethylamino)buta-1,3-dienes in 40-94% yields. All reactions were observed to consistently produce single geometrical isomers, and in cases where non-symmetrical acetylenes were employed the reactions proceeded in a regiospecific manner.     

4-羟基-3-(2-亚氨基乙基)-2H-苯并吡喃-2-酮类化合物的超声辐射合成

以乙醇为溶剂,4-羟基-3-乙酰基香豆素和胺为原料,对甲苯磺酸为催化剂,在超声波作用下合成一系列4-羟基-3-(2-亚氨基乙基)-2H-苯并吡喃-2-酮类化合物,产率62%~94%。 对产物进行了IR、1H NMR及HRMS表征,对化合物3c进行了X射线衍射分析。 该方法具有反应产率高、时间短、反应条件温和及操作简单等优点。