Efficient Synthesis of 1‐(5′‐Acylamino‐1′,3′,4′‐thiadiazol‐2′‐yl)‐4‐acyl‐thiosemicarbazides

Acyl chlorides reacted with ammonium thiocyanate and carbonic dihydrazide under phase‐transfer catalysis to first afford 2,2′‐bis(acylaminothiocarbonyl)‐carbonic dihydrazides, which further cyclized in the presence of glacial acetic acid to efficiently give 1‐(5′‐acylamino‐1′,3′,4′‐thiadiazol‐2′‐yl)‐4‐acyl‐thiosemicarbazides in high yield.     

Asymmetric Synthesis and Characterization of Chiral 2,2′‐Diamino‐3,3′‐diethoxycarbonyl‐8,8′‐diphenyl‐1,1′‐biazulene

Abstract

rac‐2,2′‐Diamino‐3,3′‐diethoxycarbonyl‐8,8′‐diphenyl‐1,1′‐biazulene was synthesized from diethyl 2‐aminoazulene‐1,3‐dicarboxylate and was optically resolved into two enantiomers of S‐form and R‐form. The enantioselective oxidative couplings with two chiral amines [(?)‐sparteine and (R)‐(+)‐α‐methylbenzylamine] and ferric chloride catalyst, and the asymmetric couplings with two chiral oxovanadium(IV) complexes of ethyl 2‐amino‐4‐phenylazulene‐1‐carboxylate, easily yielded chiral 2,2′‐diamino‐3,3′‐diethoxycarbonyl‐8,8′‐diphenyl‐1,1′‐biazulene. Therefore, the introduction of two phenyl groups at the 8‐ and 8′‐postions of each azulene ring using phenyl magnesium bromide via an addition–oxidation–decarboxylation mechanism resulted in 1,1′‐biazulene forming a chiral C₂ axis.     

Preparation of Building Blocks for Carba‐Oligosaccharides: Some Protected 5a′‐Carba‐D‐hexopyranosyl‐1,5‐anhydro‐2‐deoxy‐D‐arabino‐hex‐1‐enitols,and 5a,5a′‐Dicarba Congeners Thereof

Four configurational types of two protected O‐linked (5a‐carba‐D‐hexopyranosyl)‐D‐glucal and carba‐D‐glucal derivatives were prepared in order to provide versatile synthetic intermediates readily convertible into carba‐oligosaccharides of biological interest. These compounds may also find application as donors for elongation of carba‐oligosaccharide chains having O‐linked carbahexopyranose residues at nonreducing ends.     

Solid‐State Photodimerization of 1,2‐Bis(5′‐pyrimidyl)ethene

The photodimerization of 1,2‐bis(5′‐pyrimidyl)ethene in the solid state is reported. Photolysis of the crystalline solid formed on self‐assembly of 1,2‐bis(5′‐pyrimidyl)ethene and C‐methylcalix[4]resorcinarene and photolysis of the solid recystallized from dichloromethane yielded cis‐anti‐cis‐1,2,3,4‐tetrakis(5′‐pyrimidyl)cyclobutane as the only product. Single‐crystal X‐ray analysis of each of these solids confirms that the alkenes are π‐stacked, colinear, and separated by less than 4.2 Å.     

Facile Synthesis of 2,2′‐Dialkylated 4,4′‐Oxybiphenols

2,2′‐Alkyl‐disubstituted 4,4′‐oxybiphenols (4) were prepared in good yields through esterification of 4,4′‐oxybiphenol (1), AlCl₃‐promoted Fries rearrangement, and AlCl₃/NaBH₄‐promoted reduction reaction.     

Synthesis of 3,3′‐Di(2‐Pyridyl)‐1,1′‐Bi‐2‐Naphthol Derivatives

Abstract

A new kind of (S)‐3,3′‐dipyridyl BINOLs (3a–d) with C ₂‐symmetry were synthesized in 79–84% yields by Suzuki coupling of the diboronic acid dipinacol ester (S)‐1 containing a (S)‐binaphthyl group with bromopyridine derivatives (2a–d) followed by hydrolysis.     

First Thermal Chemoselective Synthesis of Novel 2′,3′‐Dihydro‐3′‐Hydroxy‐benzofuranylcoumarins

An attempted reaction of 4‐bromomethylcoumarin with 2‐hydroxy aromatic aldehyde/2‐hydroxy aromatic ketone at room temperature in the presence of a mild base resulted in the formation of cis‐2′,3′‐dihydro‐3‐hydroxybenzofuranylcoumarins by carbanion addition across the carbonyl carbon.     

Convenient Preparation of N,N′‐Diphenyl‐N,N′‐bis(4‐aminophenyl)‐p‐phenylenediamine

Abstract

This article describes modified conditions to prepare N,N′‐diphenyl‐N,N′‐bis(4‐aminophenyl)‐P‐phenylenediamine in 60% overall yield.     

Synthesis of Poly[2‐decyloxy‐5‐(4′‐tert‐butylphenyl)‐1,4‐phenylenevinylene] as a Light Emitting Material

In this study, a new electroluminescent poly(2‐decyloxy‐5‐(4′‐tert‐butylphenyl)‐1,4‐phenylene‐vinylene) (designated as DBP‐PPV) with no tolane‐bis–benzyl (TBB) structure defect was prepared by dehydrohalogenation of 1,4‐bisbromomethyl‐2‐decyloxy‐5‐(4′‐tert‐butyl‐phenyl) benzene (as monomer). The monomer bearing decyloxy and 4′‐tert‐butylphenyl substituents was synthesized via alkylation, bromination and Suzuki coupling reactions. The two asymmetric substituents of the monomer can suppress the formation of TBB defect during polymerization process and make the resultant polymer be soluble in common organic solvents. The structure and properties of DBP‐PPV were examined by ¹H‐NMR, FT‐IR, UV/Vis, TGA and photoluminescence (PL) analyses. Moreover, with the DBP‐PPV acting as a light‐emitting polymer, a device with sequential lamination of ITO/PEDOT/DBP‐PPV/Ca/Ag was fabricated. The electroluminescence (EL) spectrum of the device showed a maximum emission at around 546 nm, corresponding to a yellowish‐green light. The device showed a turn‐on voltage of about 8.4 V and a maximum luminescence efficiency of 0.11 cd/A at an applied voltage of 12 V.     

Synthesis of 2,2′‐Bi‐2H‐3,3′‐diaryl‐1,4‐benzothiazines from α,α‐Dibromoacetophenones and o‐Aminothiophenol

Some 2,2′‐bi‐2H‐3,3′‐diaryl‐1,4‐benzothiazines (5a–f) were synthesized from α,α‐dibromoacetophenones and o‐aminothiophenol.     

Synthesis of Novel Pyrrolo[1′,5′‐a]‐1,8‐naphthyridine Derivatives through a Facile One‐Pot Process

Novel pyrrolo[1′,5′‐a]‐1,8‐naphthyridine compounds have been synthesized through a facile one‐pot process by the reaction of the corresponding 1,8‐naphthyridines with aliphatic anhydride. The structures were established by spectroscopic data. Further X‐ray crystal analysis of 4′‐acetyl‐7‐methyl‐pyrrolo[1′,5′‐a]‐1,8‐naphthyridine (1) identifies its intriguing molecular structure and reveals the strong π‐π stacking.     

Synthesis of Potentially Bioactive Heterocycles: Thermal [3,3]Sigmatropic Rearrangement of 4‐(4′‐Aryloxybut‐2′‐ynyloxy)‐6‐methyl‐2‐pyridone

Synthesis of a number of hitherto unreported 4‐aryloxymethylene‐7‐methyl‐2,3‐dihydropyrano[3,2‐c]pyridine‐5‐ones 4a–h have been achieved in moderate yields by the thermal [3,3]sigmatropic rearrangement of 4‐(4′‐aryloxybut‐2′‐ynyloxy)‐6‐methyl‐2‐pyridone.     

Microwave‐Assisted Solvent‐Free Regiospecific Synthesis of 5‐Alkylidene and 5‐Arylidenehydantoins

Hydantoins have become a well‐known class of structures that have found significant applications as agrochemicals and therapeutics. This structural motif is of interest in the synthesis of small building blocks suitable for the preparation of potentially bioactive molecules. In this sense, 5‐alkylidene and 5‐arylidenehydantoins constitute nice examples of precursors of synthetic α‐amino acids. The microwave‐assisted synthesis of these compounds under green chemistry conditions is reported in this article. The method has proved to afford yields of 74–96%.     

Crystal structure of 1,2‐[4‐butoxybenzoyloxy‐4′‐pentyl]diphenylethane

The crystal structure of 1,2‐[4‐butoxybenzoyloxy‐4′‐pentyl]diphenylethane (C₃₀H₃₆O₃) has been determined by direct methods using single crystal X‐ray diffraction data. It crystallizes in the monoclinic system with space group P2₁/a and Z?=?4. The unit cell parameters are: a?=?8.098(1), b?=?10.926(1), c?=?29.643(2)?Å and β?=?94.01(1)°. The final reliability factor is R?=?0.073 and the goodness of fit is equal to 1.027. The molecular arrangement is very typical, with molecules associated in dimers very closely parallel to the Oz axis. In a given dimer, the backbones of the two molecules run alongside each other; this association can be attributed to strong dipole–dipole interactions through the polar ester and ether groups. In addition these dimers are connected to neighbours via dipole–dipole interactions along the Oy direction. There are numerous very weak van der Waals interactions, particularly between the terminal aliphatic chains.     

Synthesis and study of 4‐(4′‐n‐alkoxybenzoyloxybenzoyl)‐4′′‐n‐butoxyanilides

Thirteen compounds with ester and amide linkages were synthesized and their mesogenic properties evaluated. Methyl to n‐propyl derivatives exhibit nematic phases, n‐butyl to n‐decyl derivatives exhibit smectic and nematic mesophases, whereas n‐dodecyl to n‐octadecyl derivatives exhibit only smectic phases. All the smectic homologues exhibit smectic C phases. Middle members of the homologous series exhibit polymorphism of smectic mesophase. A plot of transition temperatures versus number of carbon atoms in the alkoxy chain reveals an odd–even effect for nematic–isotropic transition temperatures. Nematic–isotropic and smectic–cholesteric thermal stabilities of the prepared compounds (series I) are higher compared to those of previously reported compounds, series A, B and C. The results indicate that a simple reversal of a central linkage has a dramatic effect on the appearance of smectic mesophase in a homologous series. The structures of the synthesized compounds were characterized using elemental analysis, thin‐layer chromatography and spectral data.     

Synthesis of Some Novel bis‐Spiro[indole‐pyrazolinyl‐thiazolidine]‐2,4′‐diones

The reaction of 1H‐indol‐2,3‐diones with 1,6‐dibromohexane has resulted in the formation of new 1H‐indol‐2,3‐diones‐1,1′‐(1,6‐hexanediyl)bis in quantitative yields. These compounds have been used for the synthesis of novel [3′‐(2,3‐dimethyl‐5‐oxo‐1‐phenyl‐3‐pyrazolin‐4‐yl)spiro[3H‐indol‐3,2′‐thiazolidine]‐2,4′‐dione]‐1,1′‐(1,6‐hexanediyl)bis via bis Schiff's bases, [3‐(2,3‐dimethyl‐5‐oxo‐1‐phenyl‐3‐pyrazolin‐4‐yl) imino‐1H‐indol‐2‐one]‐1,1′‐(1,6‐hexanediyl)bis.     

Thermal analysis of 5′-deoxy-5′-iodo-2′,3′-O-isopropylidene-5-fluorouridine

The melting temperature, melting enthalpy, and specific heat capacities (C _p) of 5′-deoxy-5′-iodo-2′,3′-O-isopropylidene-5-fluorouridine (DIOIPF) were measured using DSC-60 Differential Scanning Calorimetry. The melting temperature and melting enthalpy were obtained to be 453.80 K and 33.22 J g^?1, respectively. The relationship between the specific heat capacity and temperature was obtained to be C _p/J g^?1 K^?1 = 2.0261 – 0.0096T + 2 × 10^?5 T ² at the temperature range from 320.15 to 430.15 K. The thermal decomposition process was studied by the TG–DTA analyzer. The results showed that the thermal decomposition temperature of DIOIPF was above 487.84 K, and the decomposition process can be divided into three stages: the first stage is the decomposition of impurities, the mass loss in the second stage may be the sublimation of iodine and thermal decomposition process of the side-group C₄H₂O₂N₂F, and the third stage may be the thermal decomposition process of both the groups –CH₃ and –CH₂OCH₂–. The obtained thermodynamic basic data are helpful for exploiting new synthetic method, engineering design, and commercial process of DIOIPF.     

Synthesis of 5′-deoxy-5′-[18F]fluoro-adenosine by Radiofluorination of 5′-deoxy-5′-haloadenosine Derivatives

5-Deoxy-5-[¹⁸F]fluoro-adenosine was synthesised by nucleophilic radiofluorination reactions of 5-deoxy-5-haloadenosines. The homogeneous isotope exchange in 5-deoxy-5-fluoro-adenosine was also investigated. The conversion of these reactions was found to be rather low and depends on the strength of the halogen-carbon bond: 0.248% for chloride-, 0.488% for bromide- and 1.070% for iodide-derivative; there was no reaction observed in the case of fluoro-compound.     

5′-鸟嘌呤核苷三磷酸(5′-GTP)和5′-尿嘧啶核苷三磷酸(5′-UTP)二钠盐的制备

前言核苷三磷酸是含有两个高能磷酸键的高能化合物。除了参与核糖核酸合成外,在生物体内的生命活动中起着重要的作用。ATP 主要用于供给合成细胞的物质所需要的能量,也是被称为“第二信使”的环化AMP(3′5′-cyclicAMP)的前体。而后者已知与多种生化过程有关。CTP 参与重要磷脂类的合成。GTP 在蛋白质合成中是必不可少的。UTP 是肝脏中重要解毒剂尿二磷葡萄糖醛酸(UDPG)的前体,与肝糖元、酸性粘多糖的合成密切相关。根据已知的生理功能有些兄弟研究单位作了一些临床应用试验,还值得进一步探讨。     

From Tri‐O‐Acetyl‐D‐Glucal to (2R,3R,5R)‐2,3‐Diazido‐5‐Hydroxycyclohexanone Oxime

Abstract

Methyl 3‐azido‐2,3‐dideoxy‐α/β‐D‐arabino‐ and ‐α/β‐D‐ribo‐hexopyranosides were transformed into 6‐iodo analogues via p‐tolylsulfonyl compounds. Elimination of hydrogen iodide from 6‐iodo glycosides provided methyl 4‐O‐acetyl‐3‐azido‐2,3,6‐trideoxy‐α‐ and ‐β‐D‐threo‐hex‐5‐eno‐pyranosides or 3‐azido‐4‐O‐p‐tolylsulfonyl‐2,3,6‐trideoxy‐α‐D‐threo‐ and ‐β‐D‐erythro‐hex‐5‐eno‐pyranosides. Ferrier's carbocyclization of 4‐O‐acetyl‐3‐azido‐2,3,6‐trideoxy‐α‐ and ‐β‐D‐threo‐hex‐5‐eno‐pyranosides gave (2S,3R,5R)‐2‐acetoxy‐3‐azido‐5‐hydroxycyclohexanone, which was converted into oxime. The 2‐OAc group in oxime was substituted by azide ion to yield (2R,3R,5R)‐2,3‐diazido‐5‐hydroxycyclohexanone oxime. The configuration and conformation of all products are widely discussed on the basis of the ¹H and ¹³C NMR.