Bis(amino acid) derivatives of 1,4-diamino-2-butyne that adopt a C2-symmetric turn conformation

1,4-Diamino-2-butyne was prepared from 1,4-dichloro-2-butyne via 1,4-diazido-2-butyne. Bis(amino acid) derivatives of 1,4-diamino-2-butyne having the general structure (Boc-Xxx-NHCH2C[triple bond])2 (Xxx = Ala, Phe and Met) were prepared and examined by 1H NMR spectroscopy. Using chemical shift, coupling constant and DMSO titration data it is found that these compounds adopt a C2-symmetric turn conformation featuring two intramolecular hydrogen bonds.     

Raman-spectrum investigation of 2-butyne-1,4-diol 2-butyne-1,4-diol diacetate,and 1,4-dichloro-2-butyne

Summary 2-Butyne-1,4-diol, 2-butyne-1,4-diol diacetate, and 1,4-dichloro-2-butyne exist in cisoid and transoid forms because of the operation of factors hindering free rotation of individual groups of atoms in these molecules around the corresponding single bonds.     

Synthesis of silylallene glycosides and diene diglycosides by C-glycosidation of D-glucal with 1,4-bis(trimethylsilyl)-2-butyne

[reaction: see text] Silylmethylallenyl glycosides, symmetrical and unsymmetrical diene glycosides, were synthesized by C-glycosidation with 1,4-bis(trimethylsilyl)-2-butyne in good yield. The nature of the product is controlled by the choice of Lewis acid, BF(3).OEt(2), or SnCl(4). The efficient construction of unsymmetrical diene glycosides was achieved in one pot on the basis of the order of addition of sugar starting materials.     

A Convenient and Efficient Route to 1,4-Bis（heteroaryl）-buta-1,3-diene and 4-Heteroarylbut-1-en-3-yne from 1,4-Dichlorobut-2-yne

A convenient and practical route to functionalized conjugated 1,3-enynes and 1,3-dienes is described. 1,4-Bis（heteroaryl）- 1,3-diene and 1-heteroarylbut- 1-en-3-yne derivatives were prepared from 1,4-dichloro-2-butyne and corresponding N-heteroarenes such as imidazole, pyrrole, pyrazole and indole derivatives in the presence of bases in good to high yields.     

Synthesis of benzoates of 1,4-bis(2,5-dimethyl-4-hydroxypiperidino)-2-butene and 1,4-bis-(2,5-dimethyl-4-hydroxypiperidino)-2-butyne

1,4-Bis(2,5-dimethyl-4-hydroxypiperidino)-2-butene and 1,4-bis(2,5-dimethyl-4-hydroxypiperidino)-2-butyne (II and III) were obtained by the action of 1,4-dibromo-2-butene and 1,4-dibromo-2-butyne on the form of 2,5-dimethyl-4-piperidol (I). The benzoates (IV and V) were obtained by acylation of II and III with benzoyl chloride.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 352–353, March, 1971.     

Synthesis of 1-buten-3-ynyl butyl ether and tetrolaldehyde dibutyl acetal by the action of sodium butoxide on 1,4-dichloro-2-butyne

Summary A method is proposed for the preparation of 1-buten-3-ynyl butyl ether and tetrolaldehyde dibutyl acetal by the action of sodium butoxide on 1,4-dichloro-2-butyne.     

1, 4-取代-2-丁炔共二聚反应中溶剂效应和盐效应对反应选择性的影响

PdCl~2(PhCN)~2催化的1, 4-取代-2-丁炔与烯丙基氯的共二聚反应中, 考察了不同的溶剂、不同的盐组分对生成双键的顺反异构体的影响。实验结果发现, 1, 4-二氯-2-丁炔与烯丙基氯的反应中, 不加溶剂和氯化物, 产物的双键以E式为主, 加入溶剂和氯化物, 产物以Z式为主。     

Reactions of C2H with 1- and 2-butynes: an ab initio/RRKM study of the reaction mechanism and product branching ratios

Ab initio CCSD(T)/cc-pVTZ(CBS)//B3LYP/6-311G** calculations of the C(6)H(7) potential energy surface are combined with RRKM calculations of reaction rate constants and product branching ratios to investigate the mechanism and product distribution in the C(2)H + 1-butyne/2-butyne reactions. 2-Ethynyl-1,3-butadiene (C(6)H(6)) + H and ethynylallene (C(5)H(4)) + CH(3) are predicted to be the major products of the C(2)H + 1-butyne reaction. The reaction is initiated by barrierless ethynyl additions to the acetylenic C atoms in 1-butyne and the product branching ratios depend on collision energy and the direction of the initial C(2)H attack. The 2-ethynyl-1,3-butadiene + H products are favored by the central C(2)H addition to 1-butyne, whereas ethynylallene + CH(3) are preferred for the terminal C(2)H addition. A relatively minor product favored at higher collision energies is diacetylene + C(2)H(5). Three other acyclic C(6)H(6) isomers, including 1,3-hexadiene-5-yne, 3,4-hexadiene-1-yne, and 1,3-hexadiyne, can be formed as less important products, but the production of the cyclic C(6)H(6) species, fulvene, and dimethylenecyclobut-1-ene (DMCB), is predicted to be negligible. The qualitative disagreement with the recently measured experimental product distribution of C(6)H(6) isomers is attributed to a possible role of the secondary 2-ethynyl-1,3-butadiene + H reaction, which may generate fulvene as a significant product. Also, the photoionization energy curve assigned to DMCB in experiment may originate from vibrationally excited 2-ethynyl-1,3-butadiene molecules. For the C(2)H + 2-butyne reaction, the calculations predict the C(5)H(4) isomer methyldiacetylene + CH(3) to be the dominant product, whereas very minor products include the C(6)H(6) isomers 1,1-ethynylmethylallene and 2-ethynyl-1,3-butadiene.     

Synthesis of 2-Acetyl-5,8-dihydro-1,4-dihydroxy-3-methyl Naphthalene: A Product from the Isomerisation of Diels-Alder Adducts of Both 5-Methyl- and 6-Methyl-2-acetyl-1,4-benzoquinone with 1,3-Butadiene

2-Acetyl-5,8-dihydro-1,4-dihydroxy-3-methyl-naphthalene was synthesised via Diels-Alder addition of 2-acetyl-3-methyl-1,4-benzoquinone to buta-1,3-diene followed by enolisation. It was identical with material obtained by pyridine-induced acetyl migration from the 1,3-butadiene adducts of both 3- and 6-methyl-2-acetyl-1,4-benzoquinone.     

Photolysis of Solutions of 3-tert-Butylperoxy-3-methyl-1-butyne

Photolysis of solutions of 3-tert-butyl-3-methyl-1-butyne in CD3OD and C6D12 was studied by means of ^1HNMR spectroscopy, chemical nuclear polarization of the reaction products in the range 213- 333 K, and kinetic measurements. It is shown that 3-tert-butyl-3-methyl-1-butyne decomposes primarily from a singlet electronic state. A scheme is proposed of the most probable reactions involving the radicals formed and solvent molecules. It is found that secondary processes play an important role in the initiation of the chemical nuclear polarization and the photolysis mechanism.     

The association reaction between C2H and 1-butyne: a computational chemical kinetics study

The potential energy surfaces (PES) for the reaction of the C(2)H radical with 1-butyne (C(4)H(6)) have been studied using the CBS-QB3 method. Density functional B3LYP/cc-pVTZ and M06-2X/6-311++G(d,p) calculations have also been performed to analyze the reaction energetics. For detailed theoretical calculation on the total reaction mechanism, the initial association reactions on more and less substituted C atoms of 1-butyne are treated separately followed by a variational transition state theory (VTST) calculation to obtain reaction rates. The successive unimolecular reactions from the association reaction complexes are subjected to Rice-Ramsperger-Kassel-Marcus (RRKM) calculations for reaction rate constants and product branching ratios. The calculated rate constants in the temperature range 70-295 K for both the association reactions are found to be highly temperature dependent at low temperatures, which is contrary to the experimental findings of temperature independent association rates. We have explained this observation with the help of variational nature of the transition states, and we found a "loose" transition state at low temperatures. The calculated product branching ratios for the unimolecular reactions generally agree with the available experimental data, although some channels show a significant method dependency and therefore the correlation with experiment is lost to some extent. Our detailed reaction energetics calculations confirm that the C(2)H + C(4)H(6) reaction proceeds without an entrance barrier and leads to the important products ethynylallene + CH(3), 1,3-hexadiyne + H, 3,4-hexadiene-1-yne + H, 2-ethynyl-1,3-butadiene + H, 3,4-dimethylenecyclobut-1-ene + H and fulvene + H exothermic by 25-75 kcal mol(-1), with strong dependence of the product distribution on the association mode of C(2)H with C(4)H(6), making these reactions fast under low temperature conditions of Titan's atmosphere. Therefore this study can provide a detailed picture of the complex hydrocarbon formation mechanism in the upper atmosphere.     

Indium-mediated selective introduction of a 1,3-butadien-2-yl group at the C4-position in 2-azetidinones and application of 1,3-diene-tethered 2-azetidinones in the Diels-Alder reaction

The reaction of 4-acetoxy-2-azetidinones with organoindium reagents generated in situ from indium and 1,4-dibromo-2-butyne in the presence of LiCl in DMF selectively produced 2-azetidinones which contain a 1,3-butadienyl-2-yl group at the C4-position in good yields. The Diels-Alder reaction of 4-[(1-methylene)prop-2-enyl]-2-azetidinones with a variety of dienophiles provided 2-azetidinones with valuable functional-group-substituted six-membered rings at the C4-position in good yields.     

Nouvelle synthese stereoselective de disels de botadiene-1,3 ylene-1,4 bisphosphoniums

A new way to 1,4 butadienylene bisphosphonium salts $\text{2}$ is given, using a base-catalyzed double isomerization process on acetylenic precursors $\text{3}$. The precursor can be synthetized by nucleophilic substitution of 1,4-diiodo 2-butyne with triphenylphosphine. The selection of the 1,4-dihalo 2-butyne has a strong influence on the course of the reaction which, besides that, can lead to exclusive formation of a new stabilized ylid-disalt $\text{5}$.The stereoselectivity of the t.butylamine induced double isomerization allows the isolation of the kinetic product, the (Z, E) 1,4-butadienylene bisphosphoniun salt, which is then readily converted into the more stable (E, E) isomer.     

Divergent regioselective synthesis of 2,5,6,7-tetrahydro-1H-1,4-diazepin-2-ones and 5H-1,4-benzodiazepines

A novel and simple one-pot synthesis of 3-substituted 2,5,6,7-tetrahydro-1H-1,4-diazepin-2-ones from 1,2-diaza-1,3-dienes (DDs) and N-unsubstituted aliphatic 1,3-diamines is described. Here we also report a procedure to selectively obtain alkyl 5H-1,4-benzodiazepine-3-carboxylates from the DDs and 2-aminobenzylamine. Both processes occur by means of sequential 1,4-conjugated addition followed by regioselective 7-exo cyclization. The behavior of N-methyl- and N,N'-dimethyl-1,3-diaminopropanes toward the DDs furnished pyrazol-3-ones and bis-α-aminohydrazones, respectively.     

Gas-phase reactions of aryl radicals with 2-butyne: experimental and theoretical investigation employing the N-methyl-pyridinium-4-yl radical cation

Aromatic radicals form in a variety of reacting gas-phase systems, where their molecular weight growth reactions with unsaturated hydrocarbons are of considerable importance. We have investigated the ion-molecule reaction of the aromatic distonic N-methyl-pyridinium-4-yl (NMP) radical cation with 2-butyne (CH(3)C≡CCH(3)) using ion trap mass spectrometry. Comparison is made to high-level ab initio energy surfaces for the reaction of NMP and for the neutral phenyl radical system. The NMP radical cation reacts rapidly with 2-butyne at ambient temperature, due to the apparent absence of any barrier. The activated vinyl radical adduct predominantly dissociates via loss of a H atom, with lesser amounts of CH(3) loss. High-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry allows us to identify small quantities of the collisionally deactivated reaction adduct. Statistical reaction rate theory calculations (master equation/RRKM theory) on the NMP+2-butyne system support our experimental findings, and indicate a mechanism that predominantly involves an allylic resonance-stabilized radical formed via H atom shuttling between the aromatic ring and the C(4) side-chain, followed by cyclization and/or low-energy H atom β-scission reactions. A similar mechanism is demonstrated for the neutral phenyl radical (Ph˙)+2-butyne reaction, forming products that include 3-methylindene. The collisionally deactivated reaction adduct is predicted to be quenched in the form of a resonance-stabilized methylphenylallyl radical. Experiments using a 2,5-dichloro substituted methyl-pyridiniumyl radical cation revealed that in this case CH(3) loss from the 2-butyne adduct is favoured over H atom loss, verifying the key role of ortho H atoms, and the shuttling mechanism, in the reactions of aromatic radicals with alkynes. As well as being useful phenyl radical analogues, pyridiniumyl radical cations may form in the ionosphere of Titan, where they could undergo rapid molecular weight growth reactions to yield polycyclic aromatic nitrogen hydrocarbons (PANHs).     

Synthesis of 1,4-benzothiazin-2-yl derivatives of 1,3-dicarbonyl compounds and benzothiazinone spiro derivatives by the reaction of 2-chloro-1,4-benzothiazin-3-ones with ‘push-pull’ enamines

The reaction of 2-chloro-3-oxo-3,4-dihydro-2H-1,4-benzothiazines with ‘push-pull’ enamines was investigated. The reaction with the enamines occurs at the β-carbon atom in the presence of a small excess of triethylamine. As a result, a set of 3-oxo-3,4-dihydro-2H-1,4-benzothiazin-2-yl derivatives of 1,3-dicarbonyl compounds and benzothiazinone spiro derivatives was prepared. On acidic hydrolysis of ethyl 2-ethyl-3-(methylimino)-2-(3-oxo-3,4-dihydro-2H-1,4-benzothiazin-2-yl)butanoate, a new rearrangement affording ethyl 11-ethyl-2,3-dimethyl-4-oxo-2,3,4,5-tetrahydro-1H-2,5-methano-6,1,3-benzothiadiazocine-11-carboxylate was discovered. A plausible mechanism and factors influencing the course of the reaction are discussed.     

SYNTHESIS AND THERMAL REARRANGEMENT OF 2-ALKOXYCARBONYL-3-ALKYL-4H-BENZO[b][1,4]THIAZINES

Abstract

The title compounds (4b-d) together with the benzothiazolines (5b-d) have been obtained by a reaction between 2,2′-dithiodianiline (1) and β-keto esters (2b-d). The reaction between 1 and the β-keto ester 2a gives 1,4-benzothiazine 3a in addition to the benzothiazoline 5a.

It has been established that the 1,4-benzothaizines 4b-d undergo an acid-catalysed thermal rearrangement involving a [1,3] shift of the sulfur atom, giving rise to the isomeric 1,4-benzothiazines 3b-d.     

Synthesis and photochemical reaction of 1,4-dialkyl-7-oxa-2,3,5,6-tetrakis(trifluoromethyl)bicyclohepta-2,5-diene

Diels-Alder reaction of 2,5-dialkyl-3,4-bis(trifluoromethyl)furan with hexafluoro-2-butyne gave 1,4-dialkyl-7-oxa-2,3,5,6-tetrakis(trifluoromethyl)bicyclohepta-2,5-diene. Irradiation (uv) of 1,4-diethyl-7-oxa-2,3,5,6-tetrakis(trifluoromethyl)bicyclohepta-2,5-diene afforded 1-ethyl-2,3,4,5-tetrakis(trifluoromethyl)-1,4-cyclopentadiene, ethyl 3-[l-ethyl-2,3,4,5-tetrakis(trifluoromethyl)-1,4-cyclopentadienyl] ketone, and 2,7-diethyl-3,4,5,6-tetrakis(trifluoromethyl)oxepin.     

Synthesis and Electrochemical Oxidation of Nitriles of 4-Aryl-2-carbamoylmethylthio-5-ethoxycarbonyl-1,4-dihydropyridine-3-carboxylic Acids

Nitriles of 4-aryl-2-carbamoylmethylthio-5-ethoxycarbonyl-6-hydroxy-1,4,5,6-tetrahydropyridine-3-carboxylic acids were obtained by the alkylation of 1,4,5,6-tetrahydropyridine-2-thiolate with iodoacetamide or by a three-component synthesis by condensing 2-arylmethylene-1,3-dicarbonyl compounds with 2-cyanothioacetamide in the presence of piperidine with subsequent reaction with iodoacetamide. Nitriles of 4-aryl-2-carbamoylmethylthio-5-ethoxycarbonyl-1,4-dihydropyridine-3-carboxylic acids were obtained by the dehydration of 6-hydroxy-1,4,5,6-tetrahydropyridines or with a one-reactor three-component system from 2-cyano-3-(4-methoxyphenyl)thioacrylamide, 1,3-dicarbonyl compounds, and iodoacetamide. The electrochemical oxidation of the synthesized nitriles was investigated and it was established that derivatives of 1,4,5,6-tetrahydropyridine as a rule are oxidized readily to the corresponding 1,4-dihydropyridines. A comparative analysis has been carried out of the ability of hydrogenated pyridines to be oxidized electrochemically depending on the electron-withdrawing properties of the substituents in the heterocycle.     

Photochemistry of heterocycles: VIII. photocycloaddition of acetylenic compounds to 1,3-dimethyl-6-azathymine

The photocycloadditions of 1,3-dimethyl-6-azathymine to 2-butyne-1,4-diol and 1,4-dimethoxyl-2-butyne have been studied. Three novel compounds, 7,8-bis(hydroxymethyl)-3,5-dioxo-2,4, 6-trimethyl-1,2,4-triazabicyclo [4,2,0]-7-octene (1), 7,8-bismethoxymethyl-3,5-dioxo-2,4,6-trimethyl- 1,2,4-triazabicyclo[4,2,0]-7-octene (2) and 8,9-bismethoxymethyl-4-oxo-1,3,5-trimethyl-7-oxa-2,3,5-triazaspiro[5,3]- 1,8-nonadiene (3) were obtained. The proposed reaction mechanism, which includes excited triplet complexes and biradicals as intermediates, was supported by kinetic and photophysical studies.