Synthesis and mesomorphic properties of 4-methoxyphenyl 4′- n -alkoxy-2′,3′,5′,6′-tetrafluorobiphenyl-1-carboxylates

A novel type of 4-methoxyphenyl 4′-n-alkoxy-2′,3′,5′,6′-tetrafluorobiphenyl-1-carboxylates have been synthesized. Textural observations by polarizing microscopy and DSC measurements of the phase transitions show that all of these compounds are thermotropic liquid crystals with only a nematic mesophase. The relationship between the properties and chemical structures of these compounds is discussed.     

Synthesis of asymmetricP,P-dialkyl-P′,P′-diphenylethylenediphosphine dioxides

AsymmetricP, P-dialkyl-P,P-diphenylethylenediphosphine dioxides were synthesized by the addition of dialkylphosphinous acids to diphenylvinylphosphine oxide in toluene without a catalyst and in DMSO in the presence of concentrated aqueous alkali. The method for isolating dipropyl- and dibutylphosphinous acids obtained by reactions of diethylphosphite with the corresponding alkylmagnesium bromides was improved.Deceased in 1994.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 139–141, January, 1995.     

Synthesis of Steroidal Spiro-1′,2′,4′-triazolidine-3′-thiones

Steroidal ketone thiosemicarbazones (4–6), obtained from the corresponding ketones(1–3), on oxidative cyclization with H₂O₂ at 0°C provide title compounds (7–9), respectively. The structures of these compounds have been established on the basis of their elemental analytical and spectral data.     

Synthesis of 4-Bromo-1,1′:4′,1″-terphenyl and 4-Methyl-1,1′:4′,1″-terphenyl

Russian Journal of Organic Chemistry - Possible synthetic routes to 4-bromo-1,1′:4′,1″-terphenyl and 4-methyl-1,1′:4′,1″-terphenyl have been studied. Stevens...     

Synthesis of 3,4-Biheterylthieno[2,3-b]-thiophenes. Part I: Synthesis of 3,4-Bi(1′,3′,4′-thiadiazolyl-, s-triazolyl-,1′,3′,4′-thiadiazinyl-, 1′,3′,4′-triazinyl-, thiazolyl-, 1′,3′-thiazinyl- and primidinyl)-thieno[2,3-b]thiophenes

3,4-Diamino-2,5-dicarbethoxythieno[2,3-b]thiophene ( 1 ) was allowed to react with NaNO 2 and active methylenes to afford the corresponding azo compounds 2a-c . Hydrazonyl chloride 2a was treated with carbon disulfide, phenyl isothiocyanate, benzonitrile, benzyl cyanide, malononitrile, benzalaniline, ethyl mercaptoacetate, and ethyl glycinate to give 1,3,4-thiadiazolyl-, s-triazolyl-, 1,3,4-thiadiazinyl-, 1,3,4-triazinylthieno[2,3-b]thiophenes 3-6 respectively. The reaction of 2b,c with urea, thiourea, and guanidine afforded pyrimidinyl- and thiazinylazothieno [2,3-b]thiophenes 7-10 respectively. Bithiazolylthieno[2,3-b]thiophenes 11 and 13 were synthesized by treating compound 1 with CS 2 along with halo compounds. The addition of S,S-, N,S-, and N,O-acetals to the Schiff base 14 afforded compounds 15-17 respectively.     

Synthesis of Novel 1-Arylsulfonyl-4-(1′-N-2′, 3′, 4′, 6′-tetra-O-acetyl-β-D-glucopyranosyl)thiosemicarbazides

Some 1-arylsulfonylthiosemicarbazides have been reported as fungicides1 and bacterio-static agents2. Recently, it is well documented that thiosemicarbazide is a novel class ofnon-peptide antagonists for bradykinin B2 , which is beneficial in the symptomat…     

Synthesis,structure, and physico-chemical properties of 3-methyl and 3,3-dimethyl derivatives of l-(4′,4′-dimethyl-2′,6′-dioxocyclohex-1′-yl)-3,4-dihydroisoquinoline

3,3-Dimethyl- and 3-methyl-1-(4,4-dimethyl-2,6-dioxocyclohex-1-yl)-3,4-dihydroisoquinolines have been synthesized. Crystal and molecular structures of the 3,3-dimethyl derivative have been determined. In the crystalline state this compound exists as a tautomeric form where a hydrogen atom is located at the N atom of the dihydroisoquinoline fragment of the molecule. The tautomeric equilibrium does not shift noticeably in solutions, as shown by IR, UV, and NMR spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 331–336, February, 1993.     

Synthesis of 3′,4′-Dimethoxyisoflavone Derivaties

2-(Un)substituted-3,4-dimethoxy-7-hydroxyisoflavones were synthesized. Their derivatives substituted at the phenolic hydroxyl were prepared by alkylation and acylation. Aminomethyl derivatives were also prepared.     

Synthesis and Taste Properties of 4,1′,4′,6′‐Tetrahalodeoxysucrose Analogues

The synthesis of a series of 1,4,6‐trideoxy‐1,4,6‐trihalo‐β‐d‐hexulofuranosyl 4‐deoxy‐4‐halo‐α‐d‐hexopyranosides is described. The 4‐chloro‐, 4‐bromo‐ and 4‐iodo‐4‐deoxy‐β‐d‐fructofuranosyl analogues were synthesized from a 3′,4′‐lyxo‐epoxide using the respective alkali metal halides. The corresponding 4‐halodeoxytagatofuranosyl analogues, on the other hand, were obtained by direct halide displacement of the 4′‐O‐trifluoromethanesulfonyl derivative, which was derived by regioselective sulfonylation of 1,6‐di‐O‐trityl‐β‐d‐fructofuranosyl 6‐O‐trityl‐α‐d‐glucopyranoside via its stannylene acetal. The sweetness intensities of these tetrahalodeoxy compounds strongly suggest that both size and configuration of the halogen substituents at C‐4 and C‐4′ are critical for sweetness enhancement.     

Synthesis of 3-(3′-Acetyl-5′-aroyl-1′,3′,4′-oxadiazolyl-2′)-chromones

A general method has been proposed for synthesizing 3-(3-acetyl-5-aroyl-1,3,4-oxadiazolyl-2)-chromones that has been based on conversion of 3-formylchromones to acylhydrazones and of theacylhydrazones into the heterocyclic chromones.     

Synthesis of polyester by means of polycondensation of diol ester and dicarboxylic acid ester through ester–ester exchange reaction

Based on our finding that the ester-ester exchange reaction between butyl benzoate and ethyl 4-phenylbenzoate in the presence of a metal alkoxide is faster than the ester-alcohol exchange reaction of butyl benzoate and ethanol, we investigated the synthesis of polyester through ester-ester exchange reaction under various conditions. The polycondensation of diol formate and methyl dicarboxylate in the presence of a catalytic amount of potassium tert-butoxide (^tBuOK) in diglyme at 120 °C under reduced pressure (90–100 Torr) afforded high-molecular-weight polyesters. Methyl dicarboxylate containing an amino group could be used for this polycondensation, although the corresponding diacid chloride containing an amino group was not isolable. The ester-ester exchange reaction could proceed even at the polyester backbone, and the reaction of poly(1,12-dodecamethylene isophthalate) ( PEs ₁ ) with poly(ε-caprolactone) (PCL) in the presence of ^tBuOK at 140 °C afforded a copolymer PEs ₁ -stat-PCL, the structure of which was confirmed by ¹³C NMR spectroscopy and DSC thermal analysis. A similar copolymer was also obtained by the polycondensation of dodecane-1,12-diol formate and dimethyl isophthalate in the presence of PCL and ^tBuOK at 120 °C under reduced pressure.     

X-ray diffraction study of 1,5-bis-(4′,4′,4′-trifluoro-1′-methyl-3′-oxo-but-1′-enylamino)-3-oxapentane

Specific features of the molecular and crystal structures of 1,5-bis-(4′,4′,4′-trifluoro-1′-methyl-3′-oxo-but-1′-enylamino)-3-oxapentane are determined by single crystal XRD.     

Calorimetric study of the reaction between formic acid and N,N,N′,N′-tetramethylethylenediamine from the aspect of thermal energy storage

The attack by formic acid on the nitrogen electron pairs of N,N,N,N-tetramethylethylenediamine leads to the stoichiometric salt or to many other complexes with different molar fractions. Physical and thermodynamic parameters of two adducts, obtained by calorimetric study, are discussed in terms of their use as potential phase change materials in thermal energy storage because of their large heat of fusion between 288 and 333 K.

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Zusammenfassung Bei der Einwirkung von Ameisensäure auf die Elektronenpaare von N,N,N,N-Tetramethylethylendiamin entsteht ein stöchiometrisches Salz oder mehrere andere Komplexe mit unterschiedlichem Molenbruch. Es werden physikalische und thermodynamische Parameter zweier bei der kalorimetrischen Untersuchung erhaltenen Addukte hinsichtlich ihrer Verwendung als potentielle Phasenwechselsubstanzen bei der thermischen Energiespeicherung diskutiert, da sie im Bereich 288–333 K eine große Schmelz-wärme besitzen.

     

An Improved Synthesis of 2′-Hydroxy-3′,4′,6′-trimethoxyacylophenones

A wide variety of 2′-hydroxypolymethoxyacetophenones and propiophenones, e.g. 1a and 1b are used in the synthesis of flavone and ehromone natural products.¹ Repeated attempts to prepare 1a and 1b by reacting 1,2,3,5-tetramethoxybenzene 2 with acetyl or propionyl chlorides and AlCl₃ in ether² gave products which were difficult to purify.³ We traced the problem to ring-ethoxy contaminants which were isolated and tentatively identified as 3a and 3b.     

Synthesis and characterization of phenylethynyl-terminated polyimide oligomers derived from 2,3,3′,4′-diphenyl ether tetracarboxylic acid dianhydride and 3,4′-oxydianiline

With the goal of improving processability of imide oligomers and achieving high toughness of thermosetting polyimides, a series of 4-phenylethynylphthalic anhydride(PEPA)-terminated imide oligomers prepared by the reaction of 2,3,3',4'-diphenyl ether tetracarboxylic acid dianhydride(a-ODPA) and 3,4'-oxydianiline(3,4'-ODA) with different molecular weights(degree of polymerization: n = 1?9) were formed. The resultant oligomers with different molecular weights were characterized for their chemical architecture, cure behavior, thermal properties, solubility in organic solvents and rheological characteristics. Besides, the thermal properties and tensile test of cured polyimide films were also evaluated. The imide oligomer(degree of polymerization: n = 1) has some somewhat crystalline phase, and imide oligomers(degree of polymerization: n = 2?9) showed excellent solubility(40 wt%) in N-methyl-2-pyrrolidone(NMP) and N,Ndimethylacetamide(DMAc) at room temperature. Furthermore, the rheological properties of imide oligomers showed very low melt viscosity and wider processing window. The cured films exhibited good thermal properties with the glass transition temperatures of 282?373 ?C and 5 wt% thermal decomposition temperatures higher than 551 ?C in nitrogen atmosphere. The elongation at break of the prepared films was found to be high(almost 9.3%).     

Synthesis,characterization, and investigations of antimicrobial activity of 6,6-dimethyl-3-aryl-3′,4′,6,7-tetrahydro-1′H,3H-spiro[benzofuran-2,2′-naphthalene]-1′,4(5H)-dione

Chalcone-like compounds 3a–l, 2-(benzylidene)-3,4-dihydronaphthalen-1(2H)-one, were synthesized from the addition of different benzaldehyde derivatives (2a–l) to 1,2,3,4-tetrahydro-1-napthalone (1) in basic medium. Mn(OAc)₃-mediated addition of dimedone (4) to chalcone-like compounds gave the spirobenzofuran derivatives (5a-l), 6,6-dimethyl-3-aryl-3′,4′,6,7-tetrahydro-1′H,3H-spiro[benzofuran-2,2′-naphthalene]-1′,4 (5H)-dione, in good yields. The structures of synthesized compounds 5a–l were elucidated on basis of spectral data (NMR, IR) and elemental analysis. In addition, their antibacterial activities were screened against some human pathogenic microorganisms.     

Molecular and crystal structure of 4,5,4′,5′-tetrahydro-2,2′-(1,4-phenylene)bisoxazoline

4,5,4,5-Tetrahydro-2,2-(1,4-phenylene)bisoxazoline, which is one of the most promising stabilizers-consolidators of heterochain polymers, was studied by X-ray structural analysis.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2506–2507, October, 1996.     

Synthesis of n-benzyloxycarbonyl-l-α-aminoadipic acid, α-benzyl ester

A new synthesis of N-benzyloxycarbonyl-L-α-aminoadipic acid, α-benzyl ester (1) from L-lysine monohydrochloride (2) is reported.