Arylsulfonylation of N-isobutylaniline and its derivatives: experimental study and quantum-chemical calculations

The kinetics of the reactions of benzene-substituted N-isobutylanilines 1a—h with 3-nitrobenzenesulfonyl chloride in propan-2-ol was studied at 298 K. To analyze the reactivities of compounds 1a—h in the arylsulfonylation reactions and substantiate the possible mechanism of these reactions, the geometric, electronic, and energy characteristics of the reagents and a series of model compounds were calculated by the semiempirical quantum-chemical AM1 and PM3 methods. The rate of arylsulfonylation of N-isobutylaniline and its derivatives increases directly proportional to the contributions of the s and p _z orbitals of the N atoms to HOMO of amine and of the S atoms to LUMO of sulfonyl chloride. The coefficients of these AOs can be considered as the reactivity indices of the reagents used for arylsulfonylation of substituted N-isobutylanilines with aromatic sulfonyl chlorides. It was proposed that the reaction under study is orbital-controlled.     

Ab initio studies on reaction H2C=C(OH)Li+CH3 + (CH3 -)

The possible structures and isomerizations of H₂C=C(OH)Li are studied theoretically by the gradient analytical method at RHF/6-31+G level. According to these results, reactions of H₂C=C(OH)Li with CH₃ ⁺ and CH ₃ ^- are investigated thoroughly. When H₂C=C(OH)Li reacts with CH ₃ ⁺ , H_zC=C(OH)Li firstly changes from structure1 to structure4, and then combines with CH₃ ⁺. In this reaction, the configuration of central carbon is retained. When H₂C=C(OH)Li reacts with CH ₃ ^- , structure1 firstly breaks its C-O bond to give contact ion-pair. Then through transition state16 which is similar to structure2, the attack of CH ₃ ^- from the opposite side of^-OH replaces^-OH group and inverts the configuration of carbenoid carbon atom. All the results show that the ambident reactivity of carbenoid has close relationship with the stability of special structures. Project supported by the National Natural Science Foundation of China (Grant No. 29773025).     

Heterocyclization of 5-aminothieno[2,3-c]pyridazine-6-carbonitriles

Abstract

This review describes the synthesis and reactions of 5-aminothieno[2,3-c]pyridazine-6-carbonitriles as a building blocks for the synthesis of polyfunctionalized heterocyclic compounds. The antimicrobial activity of some compounds are discussed.     

Reaction of β‐Lapachone with 1,2‐Diamines: Facile Synthesis of Novel Tetracyclic Pyrazines

The reactions of β‐lapachone (1) with 1,2‐diaminoethane (2) and 1,2‐diaminopropane (4) gave the tetracyclic pyrazine derivatives (3) and mixtures of (5) and (6), respectively, while reaction with o‐phenylene diamine (7) gave the quinoxaline derivative (8). The structure of pyrazine derivative (3) is confirmed by single‐crystal X‐ray diffraction study.     

Theory of non-local (pair site) reactivity from model static-density response functions

Activation is a fundamental and well-known concept in chemistry. It may be qualitatively defined as an increase in the chemical reactivity pattern of a molecule at a given site k when the system is locally perturbed at a different site l, say. This external perturbation arise from a localized molecular rearrangement, a substitution, a selective solvation or simply by the approach of a reagent of variable hardness. This work presents a theoretical approach intending to quantify this activation concept in the density functional framework. This is done here by first calculating the fluctuation of the electron density at a given site k for the ground state of the isolated substrate (static reactivity model) and then incorporating the substrate and model electrophile reagents in a spatial disposition related to a virtual transition structure for the parent system. This perturbation is assumed representable by local changes in the external potential. It is shown that a local approximation to the softness kernel s(r, r′) yields a simple expression for the fluctuation of the electron density δρ(r _k ), which shows that this change becomes proportional to the variation of an effective potential δu(r _k ), containing the information on the variation in the chemical potential and the external perturbing potential at site k; the proportionality constant being the local softness s ⁰(r k) at that site. The strong local approximation made to the kernel s(r, r′) causes the second reactivity site (l) to implicitly appear in the formulation through the changes in the electronic chemical potential term. It is shown that the introduction of a less restrictive approach to the linear response function, obtained from a model Kohn-Sham one-electron density matrix, leads to the same result. Non-locality is therefore self-contained in the electronic chemical potential contribution to the modified potential, and may be associated with an intramolecular charge transfer between the active sites of the ambident nucleophilic/electrophilic substrate, promoted by the presence of the reagents. The resulting formulation of pair-site reactivity is illustrated for the electrophilic attack on the CN⁻ ion by different model electrophile agents of variable hardness. It is shown that correct reactivity indexes are obtained only when the topology of the transition structure is used as a vantage point to perturb the CN⁻ ion. The calculations were performed at both density functional theory and ab-initio Hartree-Fock levels. The results show that the proposed model is independent of the method used to obtain ρ(r). Received: 30 September 1997 / Accepted: 30 December 1997     

Co(II)-Mediated and microwave assisted coupling between 2,6-diaminopyridine and nitriles. A new synthetic route to N-(6-aminopyridin-2-yl)carboximidamides

The Chinese-lantern-type Co₂(O₂CBu^t)₄{2,6-(NH₂)₂C₅H₃ N}₂ complex reacts with RCN (R = Me or Prⁿ) under microwave irradiation (MWI) to give the mononuclear amidine complexes Co(O₂CBu^t)₂{H₂N(C₅H₃ N)NHC(R)=NH} (R = Me (4a) or Prⁿ (4c)). Under microwave irradiation, the addition of 2,6-diaminopyridine to acetonitrile in the presence of the pivalate complexes Co₂(μ₂-OH₂)(O₂CBu^t)₄(HO₂CBu^t)₄ (1) or [Co(OH)_n(O₂CBu^t)_2−n ]_x (2) afforded complex 4a in higher yield compared to the corresponding reaction performed earlier without MWI. The use of MWI makes it possible to perform analogous reactions with nitriles RCN (R = Et, Prⁿ, or Ph) giving rise to complexes 4b—d, respectively. Compounds 4a—d were characterized by elemental analysis and IR spectroscopy. The structure of complex 4c was established by X-ray diffraction. Amidines H₂N(C₅H₃N)NHC(R)=NH, which formed in the coordination sphere of cobalt(II), were isolated in the free state from methanolic solutions of complexes 4a—d under the action of Na₂S and were characterized by electrospray mass spectrometry and ¹H and ¹³C{¹H} NMR spectroscopy. The reactions of 2-aminopyridine with both complexes 1 and 2 in acetonitrile under microwave irradiation produced the Co(O₂CBu^t)₂(H₂NC₅H₄N)₂ complex. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 35–42, January, 2006.     

Topochemically Controlled Redox Reactions in the System In/Sn/Cl

The difference in reactivity of the two modifications of InCl in solid state reactions with SnCl₂ is discussed. It is explained on the basis of semi‐empirical and ab initio calculations giving the density of states diagrams of InCl and the energies of possible disproportionation reactions. Their general features are discussed on the basis of a simple bonding picture for open‐packed structures involving inert pair elements. A detailed analysis of the DOS distribution allows to pinpoint the observed redox instability to a specific structural feature of α‐InCl.     

Synthese und Reaktivität von 2- und 3-hydroxylierten Dihydro-1,4-Benzoxazinen

2 can be pyrrolized to yield3 a, which in turn may be hydrolyzed with HCl to3 b. Acetylation of3 a followed by a reaction with trifluoroacetic acid (TFA) gives3 e. Elimination of ethanol from3 a or of water from3 e is not possible. Treatment of1 a with pyridine/acetic anhydride andTFA or with acetic acid/acetic anhydride affords4 a and4 b, resp. Reaction of4 b in benzene/p-toluenesulfonic acid for 2 hours yields both ethers5I and5II, whereas after 6 hours 4-acetyl-4H-1,4-benzoxazine (6) is obtained. The structures of all products are established by chemical and spectroscopic methods.

Teile aus der DissertationW. Kropp, Universität Wien, 1977.     

Hetarylamidines derived from PtIV-mediated coupling of nitriles with aminoheterocycles

The trans-[PtCl₄(EtCN)₂] complex is involved in coupling reactions (CH₂Cl₂, 30–35 °C, 10–15 min) with 2-amino derivatives of heterocyclic compounds (2-NH₂Het, where Het is pyridyl, 4-methylpyridyl, 5-methylpyridyl, 6-methylpyridyl, or thiazolyl) to form the trans-[PtCl₄{ N(H)=C(Et)NHHet}₂] complexes (1–5) with κ¹(N)-coordinated hetarylamidine ligands. The reaction with the use of 2-aminopyrimidine (2-NH₂Pym) produces the [PtCl₄(₂-NH₂Pym)₂] complex (6) as a result of complete replacement of the nitrile ligands in the [PtCl₄(EtCN)₂] complex. The compositions and structures of compounds 1–6 were confirmed by elemental analysis (C, H, N), IR spectroscopy, ¹H, ¹³C{1H}, and ¹⁹⁵Pt{¹H} NMR spectroscopy, and FAB mass spectrometry. Complex 1 was additionally characterized by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1572–1576, September, 2006.     

On the Reactivity of Metal and Organometallic Halides and Pseudohalides Towards Stannosiloxane (Ph3Sn-O-SiPh3)

Abstract

Interactions of HgX₂ (X = Cl, Br, I, SCN, CN, NCO), SbCl₃, TeCl₄, and PhTeCl₃ with Ph₃Sn-O-SiPh₃ at room temperature have been found to proceed with the simultaneous cleavage of Sn-O and Si-O bonds, invariably yielding Ph₂SnO, Ph₃SiX, and the corresponding organo-mercury, -antimony, and -tellurium derivatives. The course of the reactions suggests the instability of the Sn-O-M (M = Hg, Sb, Te) system.

GRAPHICAL ABSTRACT      

Models of biotin coenzyme reactions activated through phosphorylation

Abstract

The reactivity of models of enzymatic carboxylation reactions mediated by biotin coenzyme is presented; a possible role of the requiered ATP molecule for these reactions was investigated.

Several models of biotin activated through phosphorylation - according to the O-phosphobiotin model - are described and their reactivity to wards carboxylating agents discussed.

Models also exhibit phosphoryl transfer properties which may mimic known ATP synthesis from ADP, catalyzed by biotin carboxylases. Possible involvement of the same O-phosphobiotin structure is considered.     

Living Anionic Polymerization of 4-(α-Alkylvinyl)styrene Derivatives

Summary. The anionic polymerization of four bis-functionalized styrene derivatives with α-alkylvinyl groups have been carried out in THF at −78°C with the initiator prepared from oligo(α-methylstyryl)lithium and potassium tert-butoxide. The four monomers herein used are 4-isopropenylstyrene (4), 3-isopropenylstyrene (5), 2-isopropenylstyrene (6), and 4-(α-isopropylvinyl)styrene (7). It was found that under such polymerization conditions, the vinyl groups of both 4 and 7 are selectively polymerized and the isopropenyl and α-isopropylvinyl groups remain completely intact to afford stable living anionic polymers. As expected, the resulting polymers possessed precisely controlled chain lengths and narrow molecular weight distributions. More importantly, they also possessed the pendant isopropenyl and α-isopropylvinyl group in each monomer unit possible for further modification. On the other hand, the anionic polymerization of either 5 or 6 proceeded more or less along with the unwanted side reactions leading to chain-branching, followed by cross-linking. The positional effect of isopropenyl group on the polymerization and the cause of possible side reactions were discussed.     

Synthesis, photophysical and electrochemical properties of perfluoroisopropyl substituted binuclear phthalocyanine conjugated with a butadiyne linker

Synthesis of 1,3-butadiyne-bridged perfluoroisopropyl binuclear phthalocyanine 2 has been successfully achieved from unsymmetrical A₃B-type iodo-perfluoroisopropyl phthalocyanine by palladium-catalyzed cross-coupling with trimethylsilylacetylene and copper-catalyzed Glaser homo-coupling as key reactions. The dyad 2 essentially remains non-aggregated irrespective of solvent and concentration. Electrochemical analysis suggests oxidation is not possible whereas the molecule is more easily reduced. All the results are advantages for photodynamic therapy (PDT).     

5-硝基-2H-四唑的合成、反应性及产物晶体结构的研究

5-氨基四唑(1)经过重氮化反应得到5-硝基四唑(5), 5与甲醛反应得到2-羟甲基-5-硝基四唑(6), 6与HCl或HBr反应分别得到5-5氯代四唑(7)和5-溴代四唑(8), 采用MS, IR, ¹H NMR, ¹³C NMR等技术对这些化合物进行了表征. 用X射线单晶衍射法测定了化合物5-硝基四唑钠(4), 5和6的晶体结构. 化合物4属于三斜晶系, P-1空间群; 化合物 5和6均属于单斜晶系, P2₁空间群, 化合物6的晶胞参数a＝0.66131(18) nm, b＝0.54905(15) nm, c＝0.7566(2) nm, Z＝2, V＝0.27470(13) nm³, D_c＝1.754 g/cm³, F(000)＝128, μ＝0.160 mm^－1.     

A NOVEL REDUCTIVE CYCLIZATION OF ARYLMETHYLIDENEMALONONITRILE PROMOTED BY LOW-VALENT TITANIUM

ABSTRACT

The intermolecular and intramolecular reductive coupling reactions of arylmethylidenemalononitriles induced by low-valent titanium have been studied. A possible reaction mechanism is proposed.     

THERMAL AND PHOTOCHEMICAL REACTIONS BETWEEN α, α′-DIBROMOKETONES AND FIVE-MEMBERED HETEROCYCLES IN THE PRESENCE OF IRON NONACARBONYL

Abstract

[3 + 4] Cycloaddition reactions of 2-oxyallilic cations to furan¹ to form seven-membered oxobicyclic compounds have been known for some time. The purpose of this paper has been to try to extend the reaction to five-membered heterocycles with more aromatic character than furan. An analogy has been found between the behavior of thiophene, selenophene and tellurophene in these reactions and in oxetane-forming reactions. The higher the aromaticity of the heterocycle, the more difficult it is to achieve the formation of the seven-membered ring. Contrary to what is observed in oxetane-forming reactions, where it is not possible to isolate a stable tellurium compound, the tellurabicyclic compound was isolated and identified by spectroscopic methods in the present investigation.     

Use of thin layer spectroelectrochemistry in the study of NADH regeneration by means of an hydrogenase

Abstract

Thin layer spectroelectrochemistry is used to show that it is possible to mediate the electrochemical reduction of NADH by means of an hydrogenase. This kind of cofactor regeneration is associated to three model reactions involving the reduction of pyruvate, acetoacetylCoA and ketoglutarate.     

Synthesis, properties, and reactivity of the stilbene complex of ytterbium (PhCH=CHPh)Yb(THF)2. Crystal structure of (2,4,6-But 3C6H2O)2Yb(THF)3

The stilbene complex of ytterbium (PhCH=CHPh)Yb(THF)₂ (1) was prepared by the reaction of YbI₂(THF)₂ with a twofold excess of (PhCH=CHPh)⁻ Li⁺. Based on the data of IR and ESR spectroscopy and on the results of magnetic measurements, compound1 was characterized as a complex of divalent ytterbium with the stilbene dianion. The reactivity of complex1 toward different types of reagents was studied. The structure of the product of the reaction of1 with 2,4,6-tri(tert-butyl)phenol (2,4,6-Bu^t ₃C₆H₂O)₂Yb(THF)₃ was established by X-ray diffraction analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2345–2350, November, 1998.