Mass spectral rearrangements of 3-arylsulphonyl-2-arylthiopropenes and N-(4′-arylsulphonyl-2′-butynyl)-N-(4″-arylthio-2″-butynyl)anilines

Under electron impact the title compounds undergo skeletal rearrangement in addition to the anticipated modes of cleavage. The 3-arylsulphonyl-2-arylthiopropenes readily eliminate sulphur dioxide. Other modes of fragmentation include rearrangement to a bisaryl sulphide moiety and sulphone-sulphinate rearrangement. The formation of a bisaryl sulphide ion is analogous to the behaviour of the isomeric trans-1-arylsulphonyl-2-arylthiopropenes. N-(4′-Arylsulphonyl-2′-butynyl)-N-(4″-arylthio-2″-butynyl) anilines do not undergo any of the skeletal rearrangements mentioned above, but display the concerted loss of the arylsulphonyl and arylthio moieties. Similar eliminations have been observed from the analogous bis-sulphides and bis-sulphones.     

SYNTHESE ET REACTIVITE D'UN ESTER CYCLIQUE D'α-AMINODIPHOSPHONATE. II

Abstract

The reactions of methoxy dioxaphospholan and corresponding hydrogen phosphonate 1 with (MeN = CHCl)Cl, (MeO)₂CHNMe₂ and MeOCH₂NMe₂ have been studied.

These reactions lead either to amino diphosphonate 5 or to amino phosphonate 3 and phosphate 2. The hydrolysis and methanolysis reactions of 5 are also presented.     

Theoretical study of normal and inverse electron demand cycloaddition reactions between cyclohexadiene and 2-aryl-4,6-dinitrobenzotriazole 1-oxides

In this work, we theoretically study Diels-Alder reactions between cyclohexadiene and a series of 2-aryl-4,6-dinitrobenzotriazole 1-oxides (5a-d). Based on various calculation methods such as SCF/6–31G* and DFT/B3LYP with the 6–31G* standard basis set, we discuss the thermodynamic possibility of these reactions. The reactions between a series of 6-nitrobenzotriazole 1-oxides(5aa ₁ -ab ₁ ) and cyclohexadiene are also studied. The text was submitted by the authors in English.     

A novel multicomponent reaction between amino acids,aromatic aldehydes and p-toluenesulfonylmethyl isocyanide: an efficient and green one-pot synthesis using nanosilica

The novel diastereomeric sulfonylamide derivatives 4a–h were synthesized by multi-component reactions between (l)-α-amino acids, 1, aromatic aldehydes, 2 and p-toluenesulfonylmethyl isocyanide, 3 in water/methanol using nanosilica as a catalyst. The one-pot green reactions were carried out at room temperature with a quantitative yield in water/methanol. The yield of the reactions and products was determined and discussed. The reusablity of the catalyst is discussed.     

Reactions of diazoalkanes with unsaturated compounds. 14. Reactions of diazomethane,diazocyclopropane, and methyl diazoacetate with 1,1,2,2-tetrafluoro-3-vinylcyclobutane and 2,3,3-trifluoro-1-vinylcyclobutene to form [3+2] and [1+2] cycloadducts

The reactions of diazomethane and diazocyclopropane generated in situ with 1,1,2,2-tetrafluoro-3-vinylcyclobutane (1) and 2,3,3-trifluoro-1-vinylcyclobutene (2) proceeded at the double bond of the substituent as the 1,3-dipolar cycloaddition to form the corresponding 1-pyrazolines. Under the conditions of thermolysis (340—400 °C), the resulting cyclobutylpyrazolines 4 and 5 selectively lost the dinitrogen molecule to generate 3-cyclopropyl-1,1,2,2-tetrafluorocyclobutane (6) or 1,1,2,2-tetrafluoro-3-spiropentylcyclobutane (7), respectively, in high yields. In the presence of Pd(acac)₂, the reactions of these fluorine-containing unsaturated compounds and 2-chloro-1,1,2-trifluoro-3-vinylcyclobutane (3) with diazomethane gave rise directly to cyclopropane derivatives 6, 11, and 12, respectively. The reactions of compounds 1 and 2 with methyl diazoacetate in the presence of Rh₂(OAc)₄ proceeded analogously to yield cis- and trans-disubstituted cyclopropanes.     

Stereoselective Synthesis of 2,6‐Disubstituted Tetrahydropyridines Via Aza‐Diels‐Alder Reactions

Abstract

The aza‐Diels‐Alder reactions of (E)‐2‐(phenylthio)‐1,3‐pentadiene (2) with iminium salts gave the 2,6‐disubstituted tetrahydropyridines 3–8. Factors influencing the stereochemistry and reactivity of these reactions were also studied.     

Synthesis,characterization, and investigations of antimicrobial activity of benzopyrans,benzofurans and spiro[4.5]decanes

In this study, the radical cyclization reactions of cyclic 1,3-dicarbonyl compounds (1a–c) and α,β-unsaturated alcohols (2a–d) through Mn(OAc)₃ were performed. A series of biologically interesting dihydropyrans (3–5) and dihydrofurans (6–18) were synthesized as a result of these reactions. Spiro compounds (19–20) were obtained from the reactions of 1,3-dicarbonyl compounds and (E)-2,4-diphenyl-but-3-en-2-ol (2e). The unique structure of compound 19 was also confirmed by X-ray crystallography. In addition, the antibacterial activities of synthesized compounds were screened against some bacteria. Their zone diameters showed better results than some known antibiotics.     

Preparation of 5-Cyano-4,6-dimethyl-2H-pyran-2-one and 3-Cyano-5-methoxy-4-methyl-5H-furan-2-one via a One-Pot,Domino-Knoevenagel Process

5-Cyano-4,6-dimethyl-2H-pyran-2-one (1) has been prepared via a simple one-pot domino-Knoevenagel reaction starting from ethyl acetoacetate (2) and cyanoacetone (3). Similarly, a new racemic 3-cyano-5-methoxy-4-methyl-5H-furan-2-one (7) has been prepared from 1,1-dimethoxyacetone (6) and cyanoacetic acid (4). The new alkylidene derivatives (Z/E)-ethyl-4-cyano-3-methylbut-3-enoate (5), (Z/E)-ethyl 5-amino-4-cyano-3-methyl-5-oxopent-3-enoate (9), and (2,2-dimethoxy-1-methylethylidene)malononitrile (11) have been prepared via the Knoevenagel reactions. The easy access to these new compounds in good yields shows that ammonium acetate/acetic acid–catalyzed Knoevenagel reactions and domino-Knoevenagel reactions have a broad scope of application.     

REGIOSELECTIVITY OF METALATION OF 1,3-DITHIOLANES AND 1,3-DITHIOLANE 1-OXIDES

Abstract

Deprotonation of 1,3-dithiolane 1-oxide (3) and trans-2-phenyl-1,3-dithiolane 1-oxide (5) leads to cleavage of the derived anions. Cleavage reactions do not occur with trans-hexahydro-1,3-benzodithiole (7), its 1-oxide, or its 1,1-dioxide all of which can be metalated and alkylated quantitatively at C-2. The preparation and reactions of the sulfoxides derived from 7 are not highly stereoselective.     

THE NOVEL MACROCYCLIC AND LINEAR-CHAIN THIOETHERS FROM PERCHLOROBUTADIENE AND DITHIOLES

Compounds 3a–c, 4a, b, 5a–c, and 6a, c were obtained from the reactions of perchlorobutadiene (1) with 1,4-butanedithiol (2a), 1,5-pentanethiol (2b), and 2.2′-(ethlene-dioxyl)diethanethiol (2c) in ethanol in the presence of sodium hydroxide. Compounds 7a, b were obtained from the reactions of thioethers 3a, b with m-chlorperbenzoic acid in CHCl ₃ .     

Preparation and Reactions of Optically Active 4-Hydroxy-1,3-dioxolanes: 2-Hydroxy Aldehyde Equivalents

The preparation and reactions of optically and chemically stable (S)-4-hydroxy-1,3-dioxolane 3 as a 2-hydroxy aldehyde equivalent were explored. Hydroxydioxolane 3 was prepared by reduction of ketodioxolane 2 which was obtained from (S)-2-hydroxycarboxylic acid 1. The reactions of 3 with triethyl phosphonoacetate and organometallic reagents were carried out. These and other conversions gave synthetically and biologically useful products in moderate to good chemical and moderate stereochemical yields.     

钌1,2-萘醌-1-肟配合物对aldol C—C成键反应的催化作用

在钌1,2-萘醌-1-肟(1-nqo)配合物cis,cis-[Ru(1-nqo)₂(CO)(NCMe)] (1)或trans,trans-[Ru(1-nqo)₂(PBu₃)₂] (2)的作用下, 氰基乙酸乙酯与取代苯甲醛发生aldol C—C成键反应. 根据GC-MS检测及HPLC分离结果, 对二苯甲醛的二个醛基可分别或同时与氰基乙酸乙酯发生aldol反应. ¹H NMR表征结果证明, 二种产物的双键构型均为反式. 其它取代苯甲醛的反应均给出单一反式aldol产物, 这表明该催化反应具有立体选择性. 配合物1的催化活性稍差, 产率不超过60%, 而配合物2的催化活性要高于1, 最高产率达99%.     

The Synthesis of New S- and N,S-Substituted Halo Nitro Dienes by the Reactions of 1-Bromo-1,2,4,4-tetrachloro-3-nitrobuta-1,3-diene with Thiols and Cyclic Amines

The substituted products alkyl(aryl)thio-tetrahalo-3-nitrobuta-1,3-dienes 3a–b were obtained from the reactions of 1-bromo-1,2,4,4-tetrachloro-3-nitrobuta-1,3-diene (1) with thiols. Further reactions of the substituted product alkyl(aryl)thio-tetrahalo-3-nitrobuta-1,3-dienes 3a–b in dichloromethane reacted with piperazine derivatives and morpholine to generate 5a–b and 7a–l. The structures of the new compounds were determined by microanalysis and spectroscopic data.     

Syntheses,spectroscopic and crystallographic characterizations of 4-nitrobenzyloxy derivatives and benzofurans from <Emphasis Type="Italic">ortho</Emphasis>-substituted benzaldehydes and 4-nitrobenzyl bromide

A series of benzyloxybenzaldehyde derivatives (1–3) were prepared by the reactions of 4-nitrobenzyl bromide with 4-hydroxy-3-methoxybenzaldehyde (vanillin), 2-hydroxy-3-methoxybenzaldehyde (o-vanillin) and 2-hydroxy-4-methoxybenzaldehyde. When the reaction time is quite long, benzofuran derivatives (4 and 5) were obtained by the reactions of ortho-hydroxyaldehydes with the 4-nitrobenzyl bromide. Condensation reactions among the three benzyloxybenzaldehyde derivatives (1–3) with 2-aminomethylfuran (furfurylamine) yielded the new imine compounds (6–8). The structures of these aldehydes (1–3), benzofuran derivatives (4 and 5) and imine compounds (6–8) were confirmed on the basis of elemental analyses, IR, ¹H NMR and ¹³C NMR and mass spectroscopy. The solid-state structures of compounds 4–6 were determined by single-crystal X-ray crystallography.     

Synthesis and Reactivity of 2-(1,2,3-Dithiazol-5- Ylidene)Aminothiophenes

The reaction of aminothiophenes (1) with Appel's salt (2) affords 2-(1,2,3-dithiazol-5-ylidene)aminothiophenes (3). Under the action of ZnCl₂, the latter compounds are transformed into 1,3-oxazin-4-one systems (4). The reactions of compounds 4 with dienophiles under atmospheric or high pressure give thienopyridines (6–11); the reactions with amines produce pyrimidinones (12) and guanidines (14–15).     

EQUILIBRIA AND REACTION RATES OF PHOSPHORUS SUBSTITUTION REACTIONS IN 2-R-1,3,2-DISUBSTITUTED PHOSPHORINANES

Abstract

Equilibrium constants and reaction times were observed for six equilibria involving methanol, ethanol, dimethylamine, diethylamine and pyrrolidine with 2-R-1,3,2-dioxaphosphorinanes wherein R = MeO (1), EtO (2), Me₂N (3), Et₂N (4) and (CH₂)₄N (5), or 2-R-1,3-dimethyl-1,3,2-diazaphosphorinanes wherein R equalled the same five groups (6–10, respectively). Reaction times of amine substitutions were shorter for diaza compounds and for those reactions which contained pyrrolidine. Equilibrium constants were dependent not only upon the nucleophilicities of the exchanging groups, but also upon the steric interactions of the 2-substituents with the groups in the 1 and 3 positions. Thus, the values of K's for the equilibria 5 + Me₂NH → 3 + (CH₂)₄NH, and 10 + Me₂NH → 8 + (CH₂)₄NH were experimentally identical, whereas K for 9 + Me₂NH → 8 + Et₂NH was ca. eight times that for 4 + Me₂NH → 3 + Et₂NH. The reactions were acid catalyzed, and, for amine substitutions with 8–10, exchange could be rapid on the NMR time scale. Equilibrium positions of amine-containing reactions were [H⁺] dependent, where coordination of the less basic amine to phosphorus became increasingly favored by the addition of acid. These observations raise questions about a recent mechanistic proposal for catalyzed substitution reactions. Similar substitution reactions, such as Me₂NH with the isomeric 4-methyl analogues of 3, provide a procedure for the determination of cis-trans isomer equilibrium distributions.     

Regioselective synthesis of 2,4-disubstituted thiophenes

A highly regioselective route was established to 2-aryl-, 2-cyclohexyl-, and 2-(2-arylethyl)4-alkylthiophenes, which are potential candidates as liquid crystalline compounds of low viscosity. The key synthetic intermediates, 2-substituted-4-(chloromethyl)thiophenes 6, 14, and 20 were prepared respectively from the reactions of β, γ-epoxycarbonyl compounds 5, 13, and 19 with Lawesson's reagent in the presence of a catalytic amount of p -toluenesulfonic acid. The epoxycarbonyl compounds were obtained from the TiCl₄-mediated reactions of 2-(chloromethyl)-3-(trimethylsliyl)propene (10) with acid chlorides followed by epoxidation with m-chloroperoxybenzoic acid, or from prior epoxidation followed by oxidation with pyridinium dichromate of homoallylic alcohols 3. The homoallylic alcohols 3 were synthesized from the reactions of 2-(chloromethyl)-3-(trichlorosilyl)propene (2) with aldehydes in N, N-dimethylformamide. Copper (I) catalysed cross-coupling reactions of 2-substituted-4-(bromomethyl)thiophenes (which were prepared by transhalogenation of 2-substituted-4- (chloromethyl)thiophenes with NaBr in acetone) with Grignard reagents afforded 2,4-disubstituted thiophenes. Using this method, eleven 2,4-disubstituted thiophenes were synthesized and their potentials as liquid crystalline compound of low viscosity were examined. The synthesized 2-(4-cyanophenyl)-4-pentylthiophene was observed to have a lower melting point than the corresponding 2,5-disubstituted thiophene. This observation is consistent with the expectation from the basis of molecular linearity which can affect the viscosity and/or melting point of crystalline compounds.     

METALLAPHOSPHENES AND DIPHOSPHENES

Abstract

Transient metallaphosphenes (rbnd2;M[dbnd]P[sbnd]) have been obtained by exchange reactions between disilylphosphines and organometaldihalides (M = Ge, Sn), or by thermolysis of 2-metallaphosphetanes (M = Si, Ge). They are characterized by trapping reactions with strained heterocycles. The first stable germaphosphene 12 has been synthesized by dehydrohalogenation from the parent halogermylphosphine and isolated in form of orange crystals. It is very reactive toward compounds with active hydrogen.

Transient diphosphenes ([sbnd]P[dbnd]P[sbnd]) have been prepared by the same type of exchange reactions between disilylphosphines and dichlorophosphines and characterized by trapping reactions on dienes. The second stable diphosphene 18 has been obtained by addition of t-BuLi on trisyldichlorophosphine. Its structure has been determined by X-ray diffraction and some aspects of its reactivity are described. The reaction of bisyltrichlorogermylphosphine with DBU affords the new stable and potentially reactive diphosphene 30.     

REACTION OF AROMATIC NITRO COMPOUNDS WITH ELEMENTAL SULFUR IN LIQUID AMMONIA AND AMINES

Abstract

Aromatic nitro compounds were reduced with elemental sulfur in liquid ammonia and in amines, yielding the corresponding anilines. However, introduction of a substituent on the benzene ring or variation of the amine changed somewhat the pattern of this reaction. For example, 4-nitrotoluene (3) and 4-cyanonitrobenzene (6) were found to give not only the corresponding reduced products but also 4,4′-dicyanodiphenyl disulfide (10), formed by replacement of the nitro group, in addition to 4-cyanoaniline (9) in the reaction with elemental sulfur in liquid ammonia. Probable mechanisms of these reactions are discussed in the light of new knowledge on the similar reactions of elemental sulfur.     

Synthese und Reaktionsverhalten von 6-sec-Amino-1,3-thiazin-2-thionen

The title compounds3 have been prepared by ring transformation reactions of the isomeric 2-sec-amino-1,3-thiazine-6-thiones1 via ring-opening products2 and by special cyclocondensation reactions with thiocarboxamides8, and with iminium salts10, starting from 2,2-dichlorovinyl ketones6 in all cases. The pathways differ specifically in scope and limitations. On the other hand the intermediates2 react with alkylating agents to 2,6-di-sec-amino-1,3-thiazinium salts4, which are also available via alkylation of3 to 2-methylthio-1,3-thiazinium salts11 and aminolysis. Moreover,11 serve as useful precursors for other 1,3-thiazine derivatives by nucleophilic methylthio displacement (examples12).