New π-electron donors: Ethanediylidene-2,2′-bis(1,3-diselenole) and ethanediylidene-2-(1,3-dithiole)-2′-(1,3-diselenole)

This communication describes synthesis and electrochemical properties of new type of π-donors containing 1,3-diselenole ring, ethanediylidene-2,2′-bis(1,3-diselenole)(1a) and ethanediylidene-2-(1,3-dithiole)-2′-(1,3-diselenole)(2a). The conductivities of the charge-transfer complexes of these donors with tetracyanoquinodimethane (TCNQ) are also demonstrated.     

Reactions of selenium dichloride and dibromide with divinyl selenide: synthesis of novel selenium heterocycles and rearrangement of 2,6-dihalo-1,4-diselenanes

The synthesis of novel selenium heterocycles, 2,6-dihalo-1,4-diselenanes, 4-halo-2-halomethyl-1,3-diselenolanes and 2-halomethyl-1,3-diselenoles, based on the reactions of selenium dichloride and dibromide with divinyl selenide is described. The spontaneous rearrangement of 2,6-dihalo-1,4-diselenanes to 4-halo-2-halomethyl-1,3-diselenolanes is observed. Distillation of 4-chloro-2-chloromethyl-1,3-diselenolane leads to regioselective dehydrochlorination and the formation of 2-chloromethyl-1,3-diselenole.     

Synthesis and Downstream Reactions of 2-(Triphenylphosphino)-4,5-dicarbomethoxy-1,3-diselenole Tetrafluoroborate: X-ray Crystal Structure of a Nitroso Derivative of a 2-Ylidene-1,3-diselenole Stabilized by an Intramolecular O.Se Interaction

The title 1,3-diselenole Wittig reagent 9 has been synthesised by a new, efficient route from readily-available starting materials and reacted with a variety of functionalized aldehydes to form the corresponding 2-ylidene-1,3-diselenones 12 in respectable yields. X-ray analysis of a nitrosated derivative 14e, prepared by the reaction of 12e with isoamyl nitrite, has provided the first direct evidence for the stabilization of such systems by intramolecular oxygen-selenium interactions.     

Strain‐Promoted 1,3‐Dithiolium‐4‐olates–Alkyne Cycloaddition

Reported here is the reactivity of mesoionic 1,3‐dithiolium‐4‐olates towards strained alkynes, leading to thiophene cycloaddition products. In the process, the potential of these dipoles towards orthogonal reaction with azides, allowing efficient double ligation reactions, was discovered. A versatile process to access benzo[c]thiophenes, in an unprecedented divergent fashion, was developed and provides a new entry to unconventional polyaromatic thiophenes.     

2-(3,5-Diaryl-Δ4-1,3,4-thiadiazolin-2-yliden)-1,3-dithiole eine neue klasse elektronenreicher olefine

The dithiolium perchlorates 3a and b were smoothly converted into the phosphonium perchlorates 4a and b by reaction with tributylphosphin. Their deprotonation with butyllithium generates the methylen-phosphoranes 7 (not isolates), from which the electron-rich olefines 9a-d are obtained by successive treatment with the Δ⁴-1,3,4-thiadiazolium perchlorates 5d and e such as triethylamine. The olefine synthesis can be performed too by the reverse way, that is by the reaction of the phosphonium salts 6a-c with the dithiolium salts 3a and b under authentic conditions. In this way the electron-rich olefines 9e-h are obtained.     

Reaction of 1,3-Dibromo- and 1,3-Dichloroacetone with 2-Aminoazaheterocycles

The reactions of 1,3-dibromoacetone with 2-aminoazines and 2-aminoazoles has been carried out for the first time and the pure intermediate quaternary salts have been isolated. They undergo cyclization to the corresponding imidazoazines and imidazoazoles containing a bromomethyl group. Similar condensations were carried out with 1,3-dichloroacetone.     

2-Methylene-13-dicelenole: A precursor of tetraselenafulvalene (TSeF)

The preparation of methylene-1, 3-diselenole and its ready conversion to TSeF are discussed.     

Dearomatizing anionic cyclization and novel skeletal rearrangement: high yield formation of multiply substituted bicyclic or polycyclic spirocyclopentadienes and phenanthrene derivatives from 4-aryl 1-lithio-1,3-butadienes

Both 4-phenyl 1-lithio-1,3-butadienes and 4-naphthyl 1-lithio-1,3-butadienes underwent highly efficient and selective intramolecular nucleophilic addition of the butadienyllithium to the aromatic rings, resulting in full dearomatization of the phenyl rings and partial dearomatization of the naphthyl rings. When the reactions were carried out at lower temperatures, ipso intramolecular nucleophilic attack took place exclusively to afford the spirocyclopentadiene derivatives upon hydrolysis or further treatment with a variety of electrophiles. 4-Naphthyl 1-lithio-1,3-butadienes and 4-phenyl 1-lithio-1,3-butadienes were found to proceed in this reaction under similar conditions, with the former being faster even at -78 degrees C. However, when the reaction of 4-naphthyl 1-lithio-1,3-butadienes was carried out at higher temperatures, such as 75 degrees C, an interesting skeletal rearrangement took place to afford the vicinal attack products, tetrasubstituted phenanthrenes, via a dearomatization/rearomatization process. Mechanistic investigation revealed that the kinetically favored ipso attack intermediates might undergo thermal skeletal rearrangement via 1,2-alkyl shift.     

共轭2,4,5-三取代-1,3-噁唑中噁唑环的红外吸收光谱判定

本文定性地对三十种共轭2,4,5-三取代-1,3-噁唑的红外吸收光谱进行了研究。得出一系列此类分子的红外吸收位置、强度数据,将此数据与其分子结构相联系,并将此数据归属为九类振动模式,据此提出了一个用红外光谱定性判定此类噁唑衍生物中噁唑环的系统方法。     

Synthesis of 5(6H)-phenanthridones using Diels-Alder reaction of 3-nitro-2(1H)-quinolones acting as dienophiles

Diels-Alder reactions of 3-nitro-2(1H)-quinolones with 1,3-butadiene derivatives were carried out to give the phenanthridone derivatives under both atmospheric and high pressure conditions. Furthermore, the reactivity of 3-substituted 2(1H)-quinolones acting as a dienophile with 2,3-dimethyl-1,3-butadiene was examined using molecular orbital (MO) calculation.     

Fluorene Compounds with Intramolecular Charge Transfer Containing Dithiolylidene and Selenathiolylidene Substituents

Abstract

Condensation of polynitrofluorenes with dithiolium and selenathiolium salts in DMF leads to 9-substituted fluorenes with intramolecular charge transfer (ICT); spectral investigations show that ICT energies and intensities of ICT bands in electron absorption spectra depend substantially on heteroatomlocation but display very few dependence on the heteroatom nature (S or Se)     

Generation of acyloxyketenes from unstable mesoionic 1,3-dioxolium-4-olates and their reaction with ketenophiles to give [2 + 2] cycloadducts

Fast ring opening of mesoionic 1,3-dioxolium-4-olates, generated by Rh(2)(OAc)(4)-catalyzed decomposition of phenyldiazoacetic anhydride derivatives, to acyloxyphenylketenes was demonstrated by trapping the ketenes with several ketenophiles. Reactions of phenyldiazoacetic anhydride derivatives with several ketenophiles such as dihydrofuran, carbodiimides, and imines were carried out. No 1,3-dipolar cycloadducts of the latter with 1,3-dioxolium-4-olates were observed. Instead, only their [2 + 2]-cycloadducts with the acyloxyketenes generated by ring-opening of the initially formed 1,3-dioxolium-4-olates were isolated. In the reaction with cyclopentadiene, 1,3-dipolar cycloadducts with 1,3-dioxolium-4-olates were formed as main products along with the [2 + 2]-ketene adduct. PM3 calculation of heats of formation of 2,5-diphenyl-1,3-dioxolium-4-olate and the corresponding benzoyloxyphenylketene indicates that the ring-opened acyloxyketenes are ca. 9 kcal/mol more stable than the corresponding 1,3-dioxolium-4-olates.     

Basic hydrolysis of glyceryl nitrate esters. II. 1,2-glyceryl and 1, 3-glyceryl dinitrate esters

Kinetics of the basic hydrolysis of 1,2-glyceryl dinitrate (1,2-DNG) and 1,3-glyceryl dinitrate (1,3-DNG) esters were investigated in CO₂-free aqueous calcium hydroxide solutions. The hydrolysis reactions were carried out in a temperature controlled reactor vessel with provision for continuous N₂ sparging of the reaction mixture. Both glyceryl dinitrate esters hydrolyzed via second-order reaction at 25°C. 1,2-DNG in basic solutions isomerized to 1,3-DNG which subsequently hydrolyzed to yield products. The main hydrolysis product of 1,3-DNG was identified as glycidyl nitrate. Other products formed during the basic hydrolysis of DNGs were nitrites and nitrates.     

Cationic copolymerization of 2-vinyl-1,3-dioxane with styrene and 1,3-dioxolane

Copolymerization of 2-vinyl-1,3-dioxane with styrene and 1,3-dioxolane was carried out in methylene chloride at 0°C with triethyloxonium tetrafluoroborate as an initiator. Random copolymers were obtained from both of these monomer pairs, but attempted copolymerization of 2-vinyl-1,3-dioxane with 3,3-bis(chloromethyl)oxetane under similar conditions resulted in the homopolymer of the latter monomer. There were three structural units of 2-vinyl-1,3-dioxane in these copolymers as in its homopolymer: the “ester” unit, which was formed by vinyl addition with hydride shift followed by ring-opening rearrangement, the “vinyl” unit produced by ring-opening reaction, and the unit with a pendant 1,3-dioxane ring formed by simple vinyl addition. The fractions of the ester and vinyl units to the total 2-vinyl-1,3-dioxane units in the copolymer of 2-vinyl-1,3-dioxane with styrene decreased with decreasing 2-vinyl-1,3-dioxane content. On the contrary, the fraction of the vinyl unit in the copolymer of 2-vinyl-1,3-dioxane with 1,3-dioxolane increased slightly with decreasing 2-vinyl-1,3-dioxane content, while that of the ester unit decreased. The reactivities of the propagating species are discussed on the basis of these results.     

Polymerization studies on 1-ferrocenyl-1,3-butadiene

The polymerization behavior of 1-ferrocenyl-1,3-butadiene has been investigated by using both free-radical and anionic initiation techniques. Polymerization occurred readily under the promoting action of butyllithium; however, no polymerization occurred when azobisisobutyronitrile (AIBN) or benzoyl peroxide was employed as initiator. Copolymerizations were carried out with methyl methacrylate and styrene. The behavior of 1-ferrocenyl-1,3-butadiene in the copolymerizations was followed by dilatometric rate measurements, solution viscosity determinations, and elemental analysis. The major effect observed was a severe reduction in the intrinsic viscosities of the copolymers. An explanation for the observed behavior of 1-ferrocenyl-1,3-butadiene in these reactions is advanced.     

Cyclo- and cyclized diene polymers. XIII. γ-Ray-initiated polymerization of 1,3-dienes

The γ-ray-initiated polymerization of butadiene, isoprene, and 2,3-dimethylbutadiene-1,3 was carried out at temperatures of 20°C. and ?78°C. Polymers of butadiene and isoprene with mixed linear and cyclic structure were proved to result from the polymerization at ?78°C. A monocyclic structure was found for the 2,3-dimethylbutadiene-1,3 polymers initiated either at ?78°C. or in the thiourea canal complex at 20°C.     

Separation and preparative isolation of phenolic dialdehydes by on-line overpressured layer chromatography

The Reimer-Tiemann reaction carried out in a heterogeneous solid-liquid medium was found to give the isomeric dialdehydes 2-hydroxy-1,3-benzenedicarboxaldehyde and 4-hydroxy-1,3-benzenedicarboxaldehyde. The PRISMA model was employed to optimize the eluent mixture, and with careful choice of silica gel high-performance thin-layer chromatographic plates, the two isomers could be isolated and purified by on-line overpressured layer chromatography.     

Cyclization of 4‐Phenylthiosemicarbazide with Phenacylbromide Revisited. Formation of 1,3,4‐Thiadiazines and of Isomeric 1,3‐Thiazoles

The cyclization of 4‐phenylthiosemicarbazide with phenacylbromide, carried out in refluxing ethanol, afforded 1,3,4‐thiadiazine 1 as the major product. In contrast to a previous report, 2‐phenylimino‐4‐phenyl‐2,3‐dihydro‐1,3‐thiazol‐3‐amine ( 2 ) and not 2‐hydrazono‐3,4‐diphenyl‐2,3‐dihydro‐1,3‐thiazole ( 8 ) was formed as a side‐product. This product is the main product when the reaction is carried out in concentrated hydrochloric acid. Our findings were independently confirmed by independent syntheses of the isomeric products and by a thorough study of their reactivity. It is important to note that the product distribution of the cyclization of thiosemicarbazides with haloketones strongly depends on the substitution pattern and on the reaction conditions.     

1,3-Dipolar cycloadditions of new 2,5-bifunctionalized five-membered cyclic nitrones

A new family of five-membered cyclic nitrones bearing functional groups at positions 2 and 5 were tested in 1,3-cycloadditions with various dipolarophiles. These reactions gave the corresponding cycloadducts as single diastereomers in high yields. The reaction scope was examined, 23 compounds were isolated and fully characterized. The comparison of the reactivity was carried out by a study of reaction conversions while different nitrones or dipolarophiles were used. In addition, the exceptional reactivity of nitrone bearing benzylamino group in position 2 was studied. The formation of the nitrone complex and evaluation of its reactivity in 1,3-DC is presented.