New 1,3-dithiane type ionic liquid crystal compounds

New pyridinium type thermotropic ionic liquid crystal materials having a 1,3-dithiane ring in their central core, N -substituted-4-(5-alkyl-1,3-dithian-2-yl)pyridinium bromides ( 8 ), were synthesized. These compounds exhibited a smectic A phase over a very wide temperature range including room temperature.     

New 1,3-dioxan-type ionic liquid crystal compounds having a large dielectric constant

New pyridinium-type thermotropic ionic liquid crystal materials having a 1,3-dioxan ring in its central core: N-substituted-4-(5-alkyl-1,3-dioxan-2-yl)pyridinium bromides (6) were synthesized. The mesomorphic behaviour of these compounds and dielectric constant perpendicular to the molecular axis were measured. The principal features of these compounds are that they exhibit a smectic A phase over a wide temperature range including room temperature - for example 6f: g -9 SmA 181 I (°C)-and they have a large dielectric constant perpendicular to the molecular axis.     

New 1,3-dioxan-type ionic liquid crystal compounds having a large dielectric constant

New pyridinium-type thermotropic ionic liquid crystal materials having a 1,3-dioxan ring in its central core: N-substituted-4-(5-alkyl-1,3-dioxan-2-yl)pyridinium bromides (6) were synthesized. The mesomorphic behaviour of these compounds and dielectric constant perpendicular to the molecular axis were measured. The principal features of these compounds are that they exhibit a smectic A phase over a wide temperature range including room temperature - for example 6f: g -9 SmA 181 I (°C)-and they have a large dielectric constant perpendicular to the molecular axis.     

Synthesis of N-substituted 4-aminomethyl-1,3-dioxanes

4-(R-Amino)methyl-1,3-dioxanes were synthesized from 4-chloromethyl-1,3-dioxanes. Some of these products were converted into water-soluble pyridinium chlorides by consecutive treatment with chloroacetyl chloride and pyridine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 21–23, January, 1995.     

1,3-Dipolar cycloaddition reactions of cyclooctyne with azomethine ylides

Cyclooctyne smoothly underwent 1,3-dipolar cycloaddition with aziridines and pyridinium ylides to afford the corresponding pyrroles and indolizines in moderate to good yields.     

1,3-Dipolar cycloaddition reactions of cyclooctyne with pyridinium dicynomethylides

Cyclooctyne smoothly underwent 1,3-dipolar cycloaddition with pyridinium dicyanomethylides to afford the corresponding indolizines (8-cyario-7-azatricyclo[7.6.0.0^2,7]pentadeca-1,3,5,8-tetraenes) in excellent yields.     

Hetero-diels-alder reaction of N-cyanoaniline and pyridinium cyano-(ethoxycarbonyl)methylide with aroylketenes generated in situ in thermolysis of 6-aryl-2,2-dimethyl-1,3-dioxin-4-ones

We have used thermolysis of 6-aryl-2,2-dimethyl-1,3-dioxin-4-ones in the presence of N-cyanoaniline, pyridinium cyano(ethoxycarbonyl)methylide, and 4-hydroxybenzonitrile to obtain the corresponding 6-aryl-2-phenylamino-1,3-oxazin-4-ones, pyridinium ethoxycarbonyl(4-oxo-6-aryl-4H-1,3-oxazin-2-yl)methylides, and p-cyanophenyl esters of 3-aryl-3-oxopropanoic acids. We present the results of a preliminary investigation of the biological activity of these compounds. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 764–768, May, 2006.     

gem-Difluorination of 2,2-diaryl-1,3-dithiolanes by Selectfluor and pyridinium polyhydrogen fluoride

2,2-diaryl-1,3-dithiolanes, readily obtainable from diaryl ketones, were transformed into the corresponding gem-difluoro compounds using a novel reagent combination involving Selectfluor and pyridinium polyhydrogen fluoride (PPHF) under mild conditions in moderate to good yields.     

Organoselenium‐Catalyzed Regioselective C−H Pyridination of 1,3‐Dienes and Alkenes

An efficient approach for organoselenium‐catalyzed regioselective C−H pyridination of 1,3‐dienes to form pyridinium salts has been developed. This method was also successfully applied to direct C−H pyridination of alkenes. Fluoropyridinium reagents, or initially loaded pyridine derivatives, acted as pyridine sources in the pyridination reactions. The obtained pyridinium salts could be further converted under different conditions. This work is the first example of catalytic C‐2 direct C−H functionalization of 1,3‐dienes and the first case of organoselenium‐catalyzed C−H pyridination.     

Uncommon reaction of 2-bromomethyl-1,3-thiaselenole with pyridine and its derivatives

Regioselective reaction of 2-bromomethyl-1,3-thiaselenole with pyridine and its derivatives is followed by rearrangement with ring expansion and the formation of a bond between a nitrogen atom and a carbon in the position 2. A set of derivatives of 2,3-dihydro-1,4-thiaselenine was obtained, substituted in the position 2 by a pyridinium residue functionalized by pharmacophoric groups.     

Intramolecular C-H...O hydrogen bonding in 2-(N-pyridinia)indane-1,3-dione betaines

The existence of an intramolecular C-H...O hydrogen bond between the protons of the pyridinium ring and the oxygen atoms of the phthaloyl part of the molecule in 2-(N-pyridinia)-indane-1,3-dione betaines and their aza analogs was proved by their PMR spectra. This sort of intramolecular hydrogen bond is absent in pyridinium betaines of cyclohexane-1,3-dione and acetoacetic and malonic esters.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 379–383, March, 1979.     

Liquid crystal properties of new ionic liquid crystal compounds having a 1,3-dioxane ring

New pyridinium type chiral ionic liquid crystal materials having a 1,3-dioxane ring in the central core, (+)- N -2-methylbutyl-4-(5-alkyl-1,3-dioxan-2-yl)pyridinium bromides ( 6 ), were synthesized. Mixture A was made by adding 5.9 wt % of compound 6-3 to the ferroelectric liquid crystal mixture Merck 4655-100; its phase transitions and some liquid crystal properties were measured. In spite of a large decrease of P s for mixture A, its response time A was the same as that of Merck 4655-100. The dielectric constants perpendicular to the molecular axis for the smectic C* and smectic A phases were measured for the mixture and Merck 4655-100: in the smectic C phase, these dielectric constants were almost the same (4.5~5.5), but in the smectic A phase, the perpendicular dielectric constant of the mixture was 47.0 and that of Merck 4655-100 was 4.5.     

吡啶叶立德与查尔酮1,3-偶极环加成反应制备2-苯基-3-乙酰基中氮茚

报道在氧化剂存在下吡啶叶立德与查尔酮进行1,3-偶极环加成反应, 一锅法合成2-苯基-3-乙酰基中氮茚化合物的方法, 收率37%. 用类似的方法由α-溴代异喹啉季铵盐、查尔酮、碱和氧化剂进行反应, 可一锅法得到1-苯甲酰基-2-苯基-3-乙酰基吡咯并[2,1-a]异喹啉, 收率58%.     

Characterization and phase transition study for vesicles of fluorocarbon amphiphiles with 1,3-disubstituted glycerol structure

This paper presents the preparations and characterization of vesicles of four new fluoro-carbon amphiphiles with 1,3-disubstituted glycerol structure in common and different headgroups(OH, 1; CO_2H, 2; quaternary ammonium salt, 3; and pyridinium salt, 4). These vesicles havehigher transition temperature due to the stronger hydrophobic interaction between fluorocarbonchains. Addition of fluorocarbon additives with carboxylic acid or quaternary ammonium salt headgroup respectively shows different influences on phase behavior of vesicles of 2. These results arediscussed based on the interaction within headgroup, hydrophobicity and specific mutahydrophobicinteraction between fluoro- and hydrocarbon chains.     

Inverse electron‐demand 1,3‐dipolar cycloaddition reactions of cyclooctyne with pyridinium bis(methoxycarbonyl)methylides

Cyclooctyne underwent 1,3‐dipolar cycloaddition with pyridinium bis(methoxy‐carbonyl)methylides to afford the corresponding indolizines (8‐methoxycarbonyl‐7‐azatricyclo[7.6.0.0^2‐7]pentadeca‐1,3,5,8‐tetraenes) in good to moderate yields. Some molecular orbital considerations are also described on this reaction compared with the results on the reaction of pyridinium dicyanomethylides with cyclooctyne.     

Oxidant Promoted 1,3-Dipolar Cycloaddition of Pyridinium Ylides to Chalcones for Preparation of 1-Benzoyl-2-arylindolizines

The derivatives of 1-benzoyl-2-arylindolizine were prepared in moderate yields of 41%-78% by CrO3/Et3N promoted 1,3-dipolar cycloaddition of pyridinium N-ylides and chalcones. Under the same conditions, CrO3/Et3N promoted 1,3-dipolar cycloaddition of isoquinolinium N-ylides and chalcones provided the corresponding 1-benzoyl-2-arylpyrrolo[2,1-a]isoquinolines in 45 %-61% yields.     

Metal-free synthesis of novel indolizines from chromones and pyridinium salts via 1,3-dipolar cycloaddition,ring-opening and aromatization

A simple, efficient, and economical synthetic approach to construct a variety of stucturally novel indolizines bearing a phenolic hydroxy group has been developed through 1,3-dipolar cycloaddition of chromones and pyridinium salts. The methodology is tolerant of a wide range of functional groups and applicable to library synthesis.     

Liquid crystal properties of new ionic liquid crystal compounds having a 1,3-dioxane ring

New pyridinium type chiral ionic liquid crystal materials having a 1,3-dioxane ring in the central core, (+)- N -2-methylbutyl-4-(5-alkyl-1,3-dioxan-2-yl)pyridinium bromides (6), were synthesized. Mixture A was made by adding 5.9 wt % of compound 6?3 to the ferroelectric liquid crystal mixture Merck 4655-100; its phase transitions and some liquid crystal properties were measured. In spite of a large decrease of P_s for mixture A, its response time A was the same as that of Merck 4655-100. The dielectric constants perpendicular to the molecular axis for the smectic C* and smectic A phases were measured for the mixture and Merck 4655?100: in the smectic C phase, these dielectric constants were almost the same (4.5～5.5), but in the smectic A phase, the perpendicular dielectric constant of the mixture was 47.0 and that of Merck 4655?100 was 4.5.     

Regioselectivity in the 1,3-dipolar cycloaddition reaction of unsymmetric pyridinium dicyanomethylides with dimethyl acetylenedicarboxylate and methyl propiolate: An example of dipole-dipole control of regioselectivity?

A study of the cycloaddition behavior of a series of unsymmetric pyridinium dicyanomethylides with dimethyl acetylenedicarboxylate and methyl propiolate has been carried out. The 1,3-dipolar cycloaddition proceeds in good yield with high regioselectivity to produce the corresponding indolizines and 1:1 adducts. The reactions of isoquinolinium dicyanomethylide follow frontier orbital predictions. In contrast, polar 3-substituted pyridinium dicyanomethylides gave predominantly the corresponding 8-isomers regardless of the substituents. The results can be explained by dipole-dipole interactions.     

A Novel Coupling 1,3‐Dipolar Cycloaddition Sequence as a Three‐Component Approach to Highly Fluorescent Indolizines

Indolizines 4 and biindolizines 6 can be synthesized in moderate yields in a consecutive one‐pot three‐component process by a coupling/1,3‐dipolar cycloaddition sequence of a (hetero)arenecarbonyl chloride 1 , a terminal alkyne 2 , and a suitable 1‐(2‐oxoethyl) pyridinium bromide 3 or 5 , respectively (Schemes 1 and 2). After the Sonogashira coupling, a [2+3] cycloaddition of the in situ formed pyridinium ylide, an allyl‐type 1,3‐dipole, furnishes a cycloadduct that is instantaneously oxidatively aromatized to give the highly fluorescent indolizine derivatives that were unambiguously characterized by an X‐ray‐structure analysis of compound 4d (Fig. 1). Additionally, fluorescence studies with pyridinyl‐substituted representatives reveal not only that indolizines and biindolizines are highly interesting fluorescence dyes but that their fluorescence color can also be reversibly switched upon altering the pH of the medium.