Scandium triflate-catalyzed 6,6′-diiodination of 2,2′-dimethoxy-1,1′-binaphthyl with 1,3-diiodo-5,5-dimethylhydantoin

Scandium triflate-catalyzed iodination of 2,2′-dimethoxy-1,1′-binaphthyl with 2 equiv of 1,3-diiodo-5,5-dimethylhydantoin (DIH) proceeded to give 6,6′-diiodo-2,2′-dimethoxy-1,1′-binaphtyl in 98% yield and subsequent deprotection of methyl groups provided 6,6′-diiodo-1,1′-binaphthol, which is a useful ligand or reagent for many enantioselective transformations. Use of 2 equiv of NIS in place of DIH in the presence of scandium triflate, however, did not successfully yield 6,6′-diiodo-2,2′-dimethoxy-1,1′-binaphtyl, indicating that one of two types of iodine atoms in DIH is more reactive toward the iodination than iodine in NIS.     

Substituted 2,2′‐Bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyl Complexes of Zinc

The condensation reaction of 2,2′‐diamino‐4,4′‐dimethyl‐6,6'‐dibromo‐1,1′‐biphenyl with 2‐hydroxybenzaldehyde as well as 5‐methoxy‐, 4‐methoxy‐, and 3‐methoxy‐2‐hydroxybenzaldehyde yields 2,2′‐bis(salicylideneamino)‐4,4′‐dimethyl‐6,6′‐dibromo‐1,1′‐biphenyl ( 1a ) as well as the 5‐, 4‐, and 3‐methoxy‐substituted derivatives 1b , 1c , and 1d , respectively. Deprotonation of substituted 2,2′‐bis(salicylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyls with diethylzinc yields the corresponding substituted zinc 2,2′‐bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyls ( 2 ) or zinc 2,2′‐bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐6,6′‐dibromo‐1,1′‐biphenyls ( 3 ). Recrystallization from a mixture of CH₂Cl₂ and methanol can lead to the formation of methanol adducts. The methanol ligands can either bind as Lewis base to the central zinc atom or as Lewis acid via a weak O–H ··· O hydrogen bridge to a phenoxide moiety. Methanol‐free complexes precipitate as dimers with central Zn₂O₂ rings.     

Synthesis and hydrolytic degradation of aliphatic polycarbonate based on dihydroxyacetone

The six-membered cyclic carbonate monomer, 2,2-dimethoxy-1,3-propanediol carbonate based on dihydroxyacetone with methanol ketal protected carbonyl group, was prepared by a two-step reaction including protection and ring-closing, starting from dihydroxyacetone. The ring-opening polymerization of 2,2-dimethoxy-1,3-propanediol carbonate was carried out in bulk at 110–140°C initiated by stannous octanoate to give polycarbonate, poly(2,2-dimethoxypropane-1,3-diol carbonate). The effects of different reaction conditions including different catalyst, reaction temperature, molar ratio of monomer to initiator and polymerization time on the polymerization were investigated. Polycarbonate was obtained with the yield of 58.9–91.0%. The number average molecular weight of polycarbonate was in the range of 1.43 × 10⁴ to 13.82 × 10⁴ with polydispersity indexes from 1.31 to 1.91. The protecting ketal group was partly removed by hydrolysis using 50% trifluroacetic acid as a catalyst to give a functional polycarbonate containing 70% ketone carbonyl group, which improved the hydrophilicity of initial polycarbonate. The in vitro degradation tests were carried out in a phosphate buffer solution with pH 7.4 at 37°C, which showed that the modified polycarbonate degraded completely after 5 days.     

2,5-二甲氧基-4-氯硝基苯与硫化钠的反应

硫化钠和二硫化钠分别在95%乙醇中与2,5-二甲氧基-4-氯硝基苯反应, 原本期望得到2,5-二甲氧基-4-氯苯胺, 然而对产物结构的1H NMR, 13C NMR, MS以及元素分析结果表明, 2,5-二甲氧基-4-氯硝基苯中的硝基没有被硫化钠和二硫化钠还原成氨基, 而是其中的氯原子被硫离子(或二硫离子)取代, 分别生成了4,4’-硫代-2,2’,5,5’-四甲氧基-双硝基苯和4,4’-双硫代-2,2’,5,5’-四甲氧基-双硝基苯. 根据这个实验事实, 讨论了上述亲核取代反应的机理.     

Novel Iron-Based Polynuclear Metal Complexes [FeII(L)(CN)4]2–[FeIII(H2O)3Cl]2: Synthesis and Study of Photovoltaic Properties for Dye-Sensitized Solar Cell

A series of novel polynuclear iron-based photosensitizers (1–3) with cyano-bridged to form a molecular square were synthesized and their optical, electrochemical, and photovoltaic properties were investigated. The modification of anchoring groups with 4,4'-dicarboxy-2,2'-bipyridine, 2,2'-bipyridine, and 4,4'-dimethoxy-2,2'-bipyridine does not show significant changes on the both absorption and electrochemical properties of these iron-based dyes. This indicates that the polynuclear iron-based photosensitizers have better flexibility to regulate their physical properties of solubility, surface absorption, and thin-film formation for device preparation. The polynuclear new dyes show power conversion efficiencies ranged from 0.43 to 0.48% that is almost the best system among the published iron-based photosensitizers. These iron-based dyes were able to chemisorb on TiO₂ surface efficiently and then promoting electron injection and photocurrent generation in a dye-sensitized solar cell with solar irradiation.

     

Synthesis and Ni(0)-catalyzed oligomerization of isomeric 4,4‴-dichloroquaterphenyls

4,4?-Dichloro-1,1′ : 2′,1″ : 2″,1?-quaterphenyl ( 9 ), 4,4?-dichloro-1,1′ : 3′,1″ : 3″,1?-quaterphenyl ( 10 ), and 4,4?-dichloro-1,1′ : 4′,1″ : 4″,1?-quaterphenyl ( 11 ) were synthesized by Pd (0) catalyzed cross-coupling reaction of 4-chlorobenzeneboronic acid with 2,2′-, 3,3′-, and 4,4′-bis (trifluoromethanesulfonyloxy)biphenyl respectively. 4,4?-Dichloro-1,1′ : 2′,1″ : 2″,1?-quaterphenyl ( 9 ) and 4,4?-dichloro-1,1′ : 3′,1″ : 3″,1?-quaterphenyl ( 10 ) were oligomerized by Ni(0) catalyzed homocoupling reaction to yield white and soluble oligophenylenes. © 1993 John Wiley & Sons, Inc.     

有机二磺酸锰配合物(英)

The crystal structure of [Mn(BDA)(bpy)₂(H₂O)](H₂O)₂ (1)(BDA=6,6′-dibromo-2,2′-dimethoxy-1,1′-binaphthylene-4,4′-disulfonate, bpy=2,2′-bipyridine) composes of a manganese center which is surrounded by two nitrogen atoms from 2,2′-bipyridine and four oxygen atoms from three water and sulfonate group of BDA that also participate in H-bonding interactions to form 3D network as well as some uncoordinated water. CCDC: 277922.     

One-pot multicomponent synthesis of unsymmetrical polyhydroquinoline derivatives with 1,1’-butylenebispyridinium hydrogen sulfate as an efficient,halogen-free and reusable Brönsted ionic liquid catalyst

1,1''-Butylenebispyridinium hydrogen sulfate is an efficient, halogen-free and reusable Brönsted ionic liquid catalyst for the synthesis of ethyl-4-aryl/heteryl-hexahydro-trimehtyl-5- oxoquinoline-3-carboxylates by the one-pot condensation of dimedone, aryl/heteryl aldehydes, ethyl acetoacetate, and ammonium acetate under solvent-free conditions. This method has the advantages of high yield, clean reaction, simple methodology, and short reaction time. The ionic liquid can be recycled five times without significant loss of the catalytic activity.     

2,2′,3,3′,5,5′-Hexaphenyl-[1,1′-biphenyl]-4,4′-diols as Monomer Units for Redox Polymers: Synthesis and Polymerization Strategies

Abstract

2,2′,3,3′,5,5′-Hexaphenyl-[1,1′,-biphenyl]-4,4′-diol (Ib), which is prepared by the oxidative coupling of 2,3,6-triphenylphenol, and its oxidized form (IIIb) constitute a powerful oxidation-reduction system. The oxidative coupling reaction is carried out in the presence of molecular oxygen with copper(I) chloride as a catalyst and butyronitrile as ligand and solvent. An approach to the incorporation of such biphenols into an oxidation-reduction polymer is presented.     

Block copolymers with liquid crystalline segments

This paper describes the synthesis and characterization of polystyrene-block-poly(2,2'-dimethyl-4,4'-biphenylene phenylterephthalate)-block-polystyrene and of poly(ethylene glycol)-black-poly(2,2'-dimethyl-4,4'-biphenylene phenylterephthalate)-block-poly (ethylene glycol) block copolymers. The ABA-triblock copolymers were synthesized by condensation reaction of telechelic poly(2,2'-dimethyl-4,4'-biphenylene phenylterephthalate) with ω-hydroxy polystyrene and ω-hydroxy poly(ethylene glycol) methyl ether of different molecular weights prepared by anionic polymerization. Some aspects of the liquid crystalline behavior and the phase transitions with respect to the block copolymer composition will be discussed.     

Synthesis of spirobiindanes via bis-cyclization reaction of the 1,5-diaryl-3-pentanones catalyzed by heteropoly acids

Bis-cyclization reaction of the 1,5-diaryl-3-pentanones catalyzed by heteropoly acids (HPAs) was examined for the first time, and a series of spirobiindanes were synthesized. 1,5-Diaryl-3-pentanones were refluxed and dehydrated in toluene in the presence of 0.15 equiv of a heteropoly acid to furnish spirobiindanes in moderate to high yield. For the known 4,4′-dibromo-7,7′-dimethoxy-1,1′-spirobiindane, the yield was upgraded from 66% to 80%.     

Optically Active Helical Polymer From Anionic Polymerization of (S)-6-Acrylyl-2,2’-dimethoxy-1,1’-binaphthyl

(S)-6-Acrylyl-2,2’-dimethoxy-1,1’-binaphthyl (ADBN) was synthesized and anionically polymerized using n-BuLi as an initiator. The absolute value of specific optical rotation [α]²⁵₅₈₉ of poly-ADBN is ?118.0 and that is about 8 times that of the starting monomer ADBN. Poly-ADBN was confirmed to exist in the form of one-handed helical structure in solution by means of comparing the specific optical rotation, the CD and UV-Vis spectra with that of ADBN and the model compounds such as (S)-6-propionyl-2,2’-dimethoxy-1,1’-binaphthyl (PDBN) and (S)-6-heptanoyl-2,2’-dimethoxy-1,1’-binaphthyl (HDBN). This conclusion was also confirmed by the fact that the g-value of poly-ADBN is about 13 times as high as that of its monomer and model compounds     

钯和四齿膦配体催化剂应用于Heck反应的研究

设计合成了以联萘二胺为骨架的四齿膦配体N,N,N',N'-四(二苯基膦甲基)-(1,1'-联萘)-2,2'-二胺,并将其与钯组成的催化体系用于苯乙烯和芳卤的Heck反应,该催化体系对各种卤代芳烃都表现出了很高的催化活性.对活化底物对溴苯腈,即使底物与催化剂的物质的量比达到10 000,反应20 h几乎能达到定量转化;该催化体系对活性更低的杂环底物也取得了良好的催化效果.     

Ru/ZrO_2·xH_2O催化二氟乙酸甲酯加氢制备2,2-二氟乙醇

采用共沉淀法制备Ru/ZrO2·xH2O,以Ru/ZrO2·xH2O作为催化剂催化液相中二氟乙酸甲酯(CF2HCOOCH3)加氢制备2,2-二氟乙醇(CF2HCH2OH),并且对反应前后催化剂进行了XRD表征,考察了溶剂、搅拌速度、时间、压力和温度对加氢反应的影响。实验结果表明,在以水为溶剂、搅拌速度1000 r/min、反应时间5 h、压力2.8 MPa、温度140℃条件下,CF2HCOOCH3的转化率为100%,CF2HCH2OH的收率达到51%。     

A Ring Enlargement from Seven- to Ten-Membered-Ring sulfonamide derivatives

The reaction of 3-(dimethylamino)-2,2-dimethyl-2H-azirine ( 1a ) with 4,5-dihydro-7,8-dimethoxy-1,2-benzothiazepin-3-one 1,1-dioxide ( 4 ) in dioxane at room temperature gave the correspondingly substituted 4H-1,2,5-benzothiadiazecin-6-one 1,1-dioxide 5a in 64% yield (Scheme 2). The structure of this novel ten-membered ring-enlargement product was established by X-ray crystallography (Fig.). Under more vigorous conditions (refluxing dichloroethane), 5a was formed together with the isomeric 6a , both in low yield. The 3-(dimethylamino)-2H-azirines 1b and 1c reacted sluggishly to give the two isomeric ring-enlargement products of type 5 and 6 in yields of 24–29% and 2–4%, respectively (Table 1). Even less reactive is 2,2-dimethyl-3-(N-methyl-N-phenylamino)-2H-azirine ( 1d ), which reacted with 4 in MeCN only at 65°. Under these conditions, besides numerous decomposition products, only traces of 5d and 6d were formed. No ring enlargement was observed with the sterically crowded 1e , which bears an isopropyl group at C(2).     

Ozonolytic cleavage of cycloalkenes to terminally differentiated products

A method is described by which alkoxy hydroperoxides, obtained by ozonising cycloalkenes in alcohol solution, can be converted into terminally differentiated products by the action of metal salts. Cyclohexene and cycloheptene were converted to 1,1-dimethoxy-5-chloropentane and 1,1-dimethoxy-6-chlorohexane respectively in 47% yield, using ferric chloride. With ferrous sulphate as reactant salt, cyclooctene was converted into 1,1-dimethoxy-6-heptene. A synthesis of (Z)-4-heptenal from (Z,Z)-1,5-cyclooctadiene is also described. Fragmentation, causing the loss of one carbon atom, is a characteristic of these transformations. Other variations employed the salts as oxidants and reductants simultaneously.     

Efficient,Iron-Catalyzed Synthesis of 2-Mercaptobenzothiazole Through S-Arylation/Heterocyclization of 2-Haloaniline with Potassium Xanthate

A mild and practical method for the synthesis of 2-mercaptobenzothiazole has been developed by using iron as an efficient catalyst. The present tandem reaction process allows access to a wide range of 2-mercaptobenzothiazoles in good to excellent yields by the reaction of 2-haloaniline with potassium O-ethyl dithiocarbonate in the presence of FeF₃ as a catalyst and 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl as a ligand under an atmosphere of argon.     

Crystallographic and computational study of the structure of copper(II) 2,2′-bis(2-oxidobenzylideneamino)-4,4′-dimethyl-1,1′-biphenyl

The reaction of M(OAc)₂ with 2,2′-bis(2-hydroxybenzylideneamino)-4,4′-dimethyl-1,1′-biphenyl (H₂L1) allows the synthesis of 2,2′-bis(2-oxidobenzylideneamino)-4,4′-dimethyl-1,1′-biphenyl complexes of Cu(II) (CuL1), Co(II) (CoL1) and Ni(II) (NiL1) that were characterized by elemental analysis, FTIR spectroscopy and for CuL1 also by X-ray crystallography verifying a tetradentate binding mode of L1 via an (ONNO) motif of the two phenolic oxygen atoms and two azomethine nitrogen atoms. Recrystallization from a solvent mixture of dichloromethane and methanol promotes the formation of methanol adducts. Different binding modes of the methanol–complex were investigated using density functional theory calculations and binding energies, and thermodynamic data of the interaction are reported. The results show that the favored interaction occurs when the methanol molecule acts as a Lewis acid weakly binding via an O–H···O hydrogen bridge to a phenoxide moiety leading to an elongation of the respective M–O bond.

     

Design and Optimization of Ecofriendly One-Pot Synthesis of 2,4,5-Triaryl-1H-imidazoles by Three-Component Condensation Using Response Surface Methodology

Phase-transfer-catalyzed, highly versatile, and high-yielding protocol for the synthesis of 2,4,5-triaryl-1H-imidazoles was developed through response surface methodology (RSM). The effects of different solvents, reaction paths, and phase-transfer catalysts (PTCs) in different concentrations were envisioned. Three independent variables (catalyst, catalyst loading, and solvent volume) identified by one-factor-at-a-time (OFAT) study were screened through full factorial design at two levels. The analysis of variance results suggested the significance of catalyst PEG400 and solvent glacial acetic acid at 5 h reaction. The optimum reaction conditions suggested by the RSM were the use of PEG400 (10.61 mol%) and glacial acetic acid (10.71 mL) for 5 h cycloocondensation. The experimental yield of 4,5-diphenyl-2-nitrophenyl-1H-imidazole (97%) was in agreement with predicted yield (97.5%).     

Synthesis of 4-fluororesorcinol and 4-trifluoromethylresorcinol

Less expensive, safer, and easily scaled-up methods for the synthesis of 4-fluororesorcinol and 4-trifluoromethylresorcinol have been established, including two methods to give the former compound. One involves the reaction of Selectfluor™ reagent with 1,3-dimethoxybenzene to give 2,4-dimethoxy-1-fluorobenzene followed by hydrolysis to give 4-fluororesorcinol. The overall yield of this two-step reaction is 54%. In the second case, when Selectfluor reagent is reacted directly with resorcinol, under the best reaction conditions, 4-fluororesorcinol is obtained in 66% yield. It is, however, very difficult to separate the starting material from the mono- and difluororesorcinol products. Consequently, the two-step method is the method of choice to prepare 4-fluororesorcinol. The trifluoromethyl group was incorporated into 2,4-dimethoxy-1-iodobenzene to form 1,3-dimethoxy-4-trifluoromethylbenzene followed by mild hydrolysis to give 4-trifluoromethylresorcinol. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:229–239, 1998