Ernst Anders

• Prof. Dr.
• Retired at Friedrich Schiller University Jena

The Michael-Claisen domino (MCD) cyclization used in the lycopodine synthesis by Stork, was evaluated mechanistically using DFT calculations. Calculations suggest that a dianion is not formed, which conforms to classical dianion formation normally requiring strong kinetic bases. Instead ethoxide in ethanol produces a monoanionic species driving the...

On the basis of detailed theoretical studies of the mode of action of carbonic anhydrase (CA) and models resembling only its reactive core, a complete computational pathway analysis of the reaction between several isothiocyanates and methyl mercaptan activated by a thiolate-bearing model complex [Zn(NH(3))(3)SMe](+) was performed at a high level of...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Several enanflopure alcohols are esterified with N-acyl-4- benzylpyfidinium trifluoromethanesulfonates 7b,d,f or tetrafluoroborates 7a,c,e. These reagents, which can be generated in situ, or isolated as stable salts, are synthesized from readily available 4-alkylpyridines 3, acyl chlorides 4 and strong protic acids 6. The acyl moiety is transferred...

Three-component reactions with aldehydes, trimethylsilyl trifluoromethanesulfonate or iodide, and triphenylphosphine (TPP) yield the title compounds. The X-ray structure of the cationic part of a representative product, the (4-methylphenyl)[(trimethylsiloxy) methyl]TPP+, shows an interesting lengthening of the P+-C(α) bond compared with reported va...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Conversion of aldehydes into N-(1-chloroalkyl) pyridinium chlorides (by means of pyridine and thionyl chloride) and further reaction with 3-(2-aminophenyl)amino-5,5-dimethyl-2-cyclohexenone provide a novel and efficient route to the title compounds.

MNDO semiempirical molecular orbital theory has been used to investigate the various possible reactions open to the title compounds (eq. 2–4). Specifically, the energy differences between the compounds resulting from deprotonation in the ortho-, meta-, and para-positions of pyridine and pyridine-N-oxide are compared with those obtained from N-alkyl...

1H-Benzimidazoles, 1H-imidazo[4,5-b]pyridines, and 1H-imidazo[4,5-c]-pyridines can be synthesized readily by reaction of unisolated N-(1-chloro-alkyl)pyridinium chlorides with 1,2-benzenediamines, 2,3-pyridinediamine, and 3,4-pyridinediamine respectively.

The title compounds can be synthesized readily by reaction of primary aromatic amines with the azinium salt obtained from thionyl chloride, pyridine, and 1,2-benzenedicarboxaldehyde.

A comparison is established for the reactivity of benzaldehyde, N-(1-chlorobenzyl)pyridinium chloride or N-(1-chlorobenzyl)pyrimidinium chloride with several poorly nucleophilic and/or poorly soluble primary amines under mild experimental conditions.

The first synthesis of the title compounds 4 is described. These salts are products of a chemoselective three component reaction (eq. 1). By means of various nucleophiles, compounds 4 are transformed into the substituted products 6 (eq. 2).

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Bis(1,3,4-thiadiazolo)-1,3,5-triazinium halides 6 can be easily attacked by nucleophiles at either the C(3a) or the C(4a) position of the central six-membered (cationic) ring. Nucleophilic attack leads to at least two reaction channels, one of which has been previously detected (pathway a) and leads to novel aminals 19. In this paper we report on a...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

N-(1-Chloroalkyl)pyridinium chlorides, prepared from thionyl chloride, pyridine, and an aldehyde, readily react with N,N′-disubstituted 1,2-ethanediamine to yield imidazolidines under mild and neutral conditions.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The influence of substituents at the allene skeleton on the rate-determining step of the reaction with nucleophiles catalyzed by biomimetic zinc complexes was investigated with quantum chemical (especially DFT) methods. Additional examinations were applied to derivatives of the zinc hydroxide complex modeled in analogy to the catalytic center of ca...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

In summary, we have shown that the transformation of COS by carbonic anhydrase, which finally yields H2 S and CO2 , requires no further reactant than water in order to regenerate the most important zinc-bound hydroxide [L3 ZnOH]+ from the hydrosulfide complex. We conclude that CA is perfectly equipped by nature to perform the task of transformation...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Bis(1,3,4-thiadiazolo)-1,3,5-triazinium halides 1 can be converted into various products such as guanidines or bis(azolyl)alkanes. However, they also react with hydroxide ions in aqueous solution to form novel heterocyclic-substituted ureas 2a–i. The yields were increased from moderate to good or excellent in the presence of excess guanidine 3. The...

Based upon our preceding studies of the hydration of CO2, COS and CS2, accelerated by the carbonic anhydrase (CA) using simplified [ZnL3OH]+ complexes as model catalysts, we calculated the hydration mechanisms of both the uncatalyzed and the [ZnL3OH]+-catalyzed reactions (L = NH3) of isothiocyanates RNCS on the B3LYP/6-311+G(d,p) level of theory. I...

The aim of our present investigation is to unravel the general mode of biomimetic activation of a wide variety of cumulenes by carbonic anhydrase (CA) models. Carbonic anhydrases allow the specific recognition, activation and transfer not only of CO2 but also of heteroallenes X=C=Y such as the polar or polarizable examples COS, CS2, H2CCO, and RNCS...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A one pot synthesis of the 3,3-dimethylacroyl enol ester function found in the vibsane type diterpenes has been developed based on the Anders–Gaßner variant of the Wittig reaction (AGW reaction). This method uses easily accessible acyloxyalkylidene phosphoranes and a variety of aldehydes.

Formaldehyde reacts with diformamide (10) to give N-(hydroxymethyl) diformamide (11), which upon treatment with thionylchloride yields N-(chlormethyl)diformamide (12) together with small amounts of oxydimethylenebis(diformamide) (13). Various diformylamine derivatives, such as diformylaminomethyl formiate (14), diformylaminomethylisothiocyanate (15...

The macrocyclic ligand [13]aneN 4 ( L1, 1,4,7,10-tetra-azacyclotridecane) was reacted with Zn(II) perchlorate and CO 2 in an alkaline methanol solution. It was found that, by means of subtle changes in reaction conditions, two types of complexes can be obtained: (a) the mu 3 carbonate complex 1, {[Zn( L1)] 3(mu 3-CO 3)}(ClO 4) 4, rhombohedral cryst...

Unsymmetrical chiral secondary vicinal diamines were synthesized by applying a modified three-step reaction. The key step in this sequence is a primary amine mediated ring opening reaction of a diastereomeric oxazolidinone derivative. A possible mechanism for this step is described.

In the title compound, [Zn(C11H26N4)(C11H9S)]ClO4, the ZnII atom is five-coordinated by four N atoms from a neutral 1,4,8,12-tetra­azacyclo­penta­decane aza-macrocycle mol­ecule, and one S atom from an azulenylmethane­thiol­ate ligand. Only monomers are found in the crystal. The coordination geometry can be described as trigonal bipyramidal, with t...

In the title compound, C18H28N2O4, the molecule displays a partially eclipsed conformation with an N—C—C—N torsion angle of 67.93 (s.u.?)° linking the two ethoxycarbonylcyclopentenyl groups. This conformation is different from the staggered conformation observed in the related N,N′-ethylenediamine with a cycloalkene residue. Molecules are linked by...

The crystal structure of the title compound, [Zn(C30H28BN6)(C7H7S)], is closely related to a series of other tripod zinc thiol­ates. The Zn atom adopts a very distorted tetra­hedral coordination geometry. In addition to the crystallographic data, ¹¹B NMR as well as ¹¹B-decoupled ¹H NMR data are provided. A proton shift for the boron-bound hydride (...

The title compound, [Zn(C7H7S)(C9H21N3)]SCN, features a cationic Zn complex with the metal atom in a distorted tetra­hedral environment. The crystal packing is stabilized by N—H⋯N and N—H⋯S hydrogen bonds. However, one of the amino H atoms is not involved in hydrogen bonding.

Some aspects of the catalytic mechanism of HCA have been investigated. Either a zinc-bound water or a zinc-bound hydroxide has been considered as a nucleophile attacking CO 2. No reaction path exists in the former case, while a transition state for the nucleophilic attack has been located in the latter (barrier of 7.6 kcal mol−1). This activation e...

Carbonic anhydrase (CA) is known to react with carbonyl sulfide, an atmospheric trace gas, whereby H(2)S is formed. It has been shown that, in the course of this reaction, the active catalyst, the His(3)ZnOH structural motif, is converted to its hydrosulfide form: His(3)ZnOH+COS-->His(3)ZnSH+CO(2). In this study, we elucidate the mechanism of react...

In this study, we focus on the structure–reactivity relationship of cationic zinc thiolate complexes with the general formula [Zn(Ln)(SR)]ClO4 (Ln: n-dentate azamacrocyclic ligand; R = phenylmethyl). The complexes feature macrocyclic ligands with ring sizes varying from 11 to 16 atoms and possess three or four nitrogen donors (three of them contain...

In the title compound, C18H28N2O4, the mol­ecule displays a partially eclipsed conformation with an N—C—C—N torsion angle of 67.93 (s.u.?)° linking the two ethoxy­carbonyl­cyclo­pentenyl groups. This conformation is different from the staggered conformation observed in the related N,N′-ethyl­enediamine with a cyclo­alkene residue. Mol­ecules are li...

This Perspective starts with the discussion of the properties of an interesting metalloenzyme (carbonic anhydrase, CA) that performs extremely successfully the activation of carbon dioxide. Conclusions from that are important for many synthetic procedures and include experimental and theoretical investigation (DFT calculations) of such metal mediat...

AMI- und PM3-Rechnungen ergeben eine befriedigende Korrelation zwischen den Ladungsdichten der C-5-Atome (qC-5, Tab. 2) und der Enamin-Nucleophilie der Verbindungen 1, 2, 4a-c gegenüber Enonen 3 und 9. Darüber hinaus deckt sich in dieser Reihe die Ähnlichkeit der qC-5-Werte mit der Ähnlichkeit der 13C-NMR-Verschiebungen dieser Zentren. Die erwartet...

Light-driven metallo-organic catalysis: Intramolecular photoelectron transfer in the heterodinuclear complex 1 facilitates the photocatalytic production of hydrogen and the selective hydrogenation of tolane to give cis-stilbene. All three well-coordinated parts of the supramolecular system are essential: the (tbbpy)2Ru fragment as a photoactive uni...

Chiral examples of phosphazene bases 2a–c were synthesized by treatment of (S)-2-(dialkylaminomethyl)pyrrolidine 1a–c, derived from 5-oxo-(S)-proline, with phosphorus pentachloride and subsequent addition of gaseous ammonia. The phosphazenes 2a–c were isolated as HBF4 salts in high yields and fully characterized by 1H, 13C and 31P NMR spectroscopy,...

The thiolate complexes [Zn([15]aneN4)(S–CH2–C6H5)]ClO4 (1) ([15]aneN4 = 1,4,8,12-tetraazacyclopentadecane) and [Zn(i-[14]aneN4)(S–CH2–C6H5)]ClO4 (2) (i-[14]aneN4 = 1,4,7,11-tetraazacyclotetradecane) have been reacted with carbon disulfide. The trithiocarbonate complexes [Zn([15]aneN4){S–C(S)–S–CH2–C6H5}]ClO4 {1a, monoclinic, space group P21/n, Z =...

A series of 24 novel zinc thiolate complexes containing saturated macrocyclic polyamine ligands with the general formula [Zn(Ln)(SR)]ClO4 (Ln: n-dentate azamacrocyclic ligand) has been synthesized. Two different thiolate ligands (R = phenyl, benzyl) and 12 macrocyclic ligands with ring sizes varying from 11 to 16 atoms and containing three, four, a...

Das vollständige Manuskript dieser Zuschrift erscheint in: Angew. Chem. Suppl. 1982, 675. DOI: 10.1002/ange.198206750

An efficient method for the preparation of hindered chiral guanidines using cyanogen bromide is described. The reaction between BrCN and vicinal diamines derived from (S)-2-(N,N-dialkyl-aminomethyl)-pyrrolidines provides chiral substituted cyanamides. The cyanamide derivatives reacted with secondary amines in hexafluoroisopropanol at reflux to form...

A high-pressure cell for Raman spectroscopical applications has been developed. By using this cell, it is possible to investigate reactions between solids and gases, applying pressures up to 3000 bar. The cell has been successfully tested on the reaction between ferrocene and carbon monoxide. The results point towards a multi-step reaction mechanis...

A series of novel S,N-heterocyclic (thiazolyl) substituted carboximidamides 3 and 4 was synthesized in yields up to 82% from specific triazinium salts 1 and primary or secondary amines 2 which additionally bear pyridine or imidazole units. These carboximidamides are used as tailor-made ligands for the complexation of Cu(II) and Zn(II). The coordina...

The 4-alkylidene-4H-pyridin-1-ides 1(–), which are ambident anions derived from azomethines 1a–e, react easily with CS2 to yield the lithium 2,3-dihydro-1,3-thiazole-5-thiolates 3a–e. Two mechanisms are basically possible for this cyclization: a concerted process similar to a 1,3-dipolar cycloaddition or a two-step reaction which starts with a Cα C...

In this article we performed an extensive density functional [BP86/6-311++G(3df,3pd) level] investigation of the hypersurface of the Mitsunobu reaction. Reaction of a phosphine with a dialkyl azodicarboxylate (first step in the Mitsunobu conversion) leads to either a five-membered oxadiazaphosphole ring (more stable) or a betaine. The subsequent fo...

The synthesis and properties of three bidentate zinc(II) complexes with several chiral bidentate and one molybdenum(0) with analogous tridendate neutral chiral guanidine ligands are reported. N′,N″-Diisopropyl-(S)-2-(N,N-dialkylaminomethyl) pyrrolidine-1-carboximid-amides 1–3 reacted with anhydrous zinc(II) chloride to form mono-ligand complexes 4–...

1,2-Diazetines (1) can be acylated with isocyanates (2) to give semicyclic urea derivatives (3). In contrast, isothiocyanates (4) react with 1 under mild conditions to furnish new derivatives of 1,3,4-thiadiazine (5). DFT calculations show that two different mechanistic pathways for this ring transformation are possible. N-Acylation is preferred at...

Starting with bis([1,3,4]thiadiazolo)[1,3,5]triazinium halides 1, a novel class of heterocyclic compounds, the [1,3,4]thiadiazolo[2,3-d][1,2,4]triazolo[1,5-a][1,3,5]triazinium halides 5 were prepared. The reaction between 5 and primary or secondary amines 6 yielded highly substituted guanidines 8 and fused tricyclic bis([1,2,4]triazolo)[1,5-a:1′,5′...

The transition-metal-catalyzed [2+2+1] cycloaddition reaction of 1,4-diazabutadienes, in which the imine-carbon atoms are part of an oxazine ring system, with ethylene and carbon monoxide leads to the regioselective formation of pyrrolidinone derivatives. To explain this regioselectivity, the transition states and intermediates of the rate-determin...

Novel azomethines 3 synthesized from 4-(aminomethyl)pyridine (1) and various ketones 2 exhibit a higher acidity of the Cα-protons compared with other 4-alkylpyridines like 4-benzylpyridine or 4-(tosylmethyl)pyridine. Therefore, they can easily be metalated to give a variety of specific anions 3(−), which deserve interest for further synthetic appli...

We have extended our investigations of the carbonic anhydrase (CA) cycle with the model system [(H(3)N)(3)ZnOH](+) and CO(2) by studying further heterocumulenes and catalysts. We investigated the hydration of COS, an atmospheric trace gas. This reaction plays an important role in the global COS cycle since biological consumption, that is, uptake by...

A realistic picture of the complete insertion reaction for a representative example of the formation of carbamates from lithium amides is given by combining experimental information with detailed DFT investigations. The chiral lithium (S)2-(pyrrolidin-1-ylmethyl)pyrrolidide (2) reacts with CO2 to form its corresponding carbamate. In this reaction t...

The reaction of commercially available heterocumulenes (isothiocyanates, isocyanatobenzene, N,N′-isopropylcarbodiimide) with lithiated chiral diamines 4 provided a novel class of chiral thioureas 8, ureas 9 and guanidines 10, which were isolated in good to excellent yields (60–96%). The molecular structures of compounds 8–10, derived from (S)-2-(N,...

For Abstract see ChemInform Abstract in Full Text.

Masses of evidence: Mass spectrometry combined with 18O labeling reveals that the imidazole and pyridine complexes [LnZnOH]+ (n=1, 2) are capable of activating carbon dioxide, under thermal conditions. These gas-phase reactions thus provide a simple mimic for the function of the active site in carbonic anhydrase.

The reaction of bis(1,3,4-thiadiazolo)-1,3,5-triazinium halides with primary aromatic amines in CHCl3/Et3N yields new highly substituted aromatic guanidines (up to 90% yield).

Negative hyperconjugation is a general phenomenon that can be observed in many areas of chemistry. The knowledge of its impact on structural parameters and conformational issues is well established, but little is known about its importance for chemical reactivity. Here we present a systematic study of different aspects of negative hyperconjugation...

The formation of highly reactive zwitterionic triaziniumimidothioate intermediates 10 from bis(1,3,4-thiadiazolo)-1,3,5-triazinium halides is reported. These intermediates are the first structures to be isolated from the reaction pathway between bis(1,3,4-thiadiazolo)-1,3,5-triazinium halides 1 and benzylamines 2. The reaction between 1 and 2 has a...

The cover picture shows a calculated [DFT-(B3LYP/6-311++G(d,p) level] “standardized” structure of the title compounds, the highly reactive triazinium-imidothioates (center). These are readily accessible by the reaction of an amine with a bis(thiadiazolo)-triazinium salt which is followed by deprotonation (top) and a spontaneous ring opening step. T...

The [2+2+1] cycloaddition reaction of 1,4-diazabutadienes, carbon monoxide and ethylene catalyzed by iron carbonyl complexes produces pyrrolidin-2-one derivatives. Only one of the two imine moieties is activated during the catalysis. The mechanism of this cycloaddition reaction is studied by density functional theory at the B3LYP/6-311++G(d,p) leve...

A His-X-His pseudotripeptide zinc complex (X is a N-alkyl glycine derivative) similar to the catalytic center of the carbonic anhydrase was computer designed and experimentally synthesized. Using 2D-NMR techniques, all proton, carbon chemical shifts and nuclear overhauser effect signals were assigned. The three-dimensional structure of the complex...

A convenient synthesis of chiral lithium N-alkyl carbamates 1a–4a from chiral pyrrolidines 1–4, LiH and CO2 is described. The yields are good to excellent. A combined experimental (1H, 6Li-HOESY, cryoscopy) and theoretical study (B3LYP/6-311++G(d,p)) succeeded in assigning the predominant solution state structure of 1a.

The reaction of bis([1,3,4]thiadiazolo)[1,3,5]triazinium bromides 3 with 1H[1,2,4]triazole 6, imidazole 7, 1-methylimidazole 8, and benzimidazole 9 in pyridine solution yielded product mixtures containing the highly substituted guanidines N-[[(1H-azolyl)[1,3,4]thiadiazol-3(2H)-yl]methylene][1,3,4] thiadiazol-2-amines 10, 11, 12 as main products, an...

The Collaborative Research Center (CRC) 436 'Metal-Mediated Reactions Modeled after Nature' was founded for the express purpose of analyzing the catalytic principles of metallo-enzymes in order to construct efficient catalysts on a chemical basis. The structure of the active center and neighboring chemical environment in enzymes serves as a focal p...

A quantitative structure-reactivity relationship has been derived from the results of B3LYP/6-311+G calculations on the hydration of carbon dioxide by a series of zinc complexes designed to mimic carbonic anhydrase. The reaction mechanism found is general for all complexes investigated. The reaction exhibits a low (4-6 kcal/mol) activation energy a...

The reaction of bis(1,3,4-thiadiazolo)-1,3,5-triazinium (or "5/6/5") halides 1 with 1,4,8,11-tetraazacyclotetradecane (2) and tris(2-aminoethyl)-amine (6) yields new N-functionalized cyclams (3a-d) as well as the complex tertiary amine 7. All of the NH or NH2 groups in 2 and 6 are transformed into (chiral) guanidyl moieties. The structure of a repr...

A recently developed force field with fluctuating atomic charges has been parametrized to implement calculations for zinc complexes. The atomic charges are calculated by means of a semi-empirical quantum chemical method (bond polarization theory, BPT ). The major goal of this new force field is reliable description of the geometry of zinc complexes...

The full reaction path for the conversion of carbon dioxide to hydrogencarbonate has been computed at the B3LYP/6-311+G** level, employing a [(NH(3))(3)Zn(OH)](+) model catalyst to mimic the active center of the enzyme. We paid special attention to the question of how the catalytic cycle might be closed by retrieval of the catalyst. The nucleophili...

The full reaction path for the conversion of carbon dioxide to hydrogencarbonate has been computed at the B3LYP/6-311+G** level, employing a [(NH3)3Zn(OH)]+model catalyst to mimic the active center of the enzyme. We paid special attention to the question of how the catalytic cycle might be closed by retrieval of the catalyst. The nucleophilic attac...

The conversion of CS(2) with common carbonic anhydrase model systems has been studied using Hartree-Fock and density-functional theory methods employing the 6-311+G basis set. The calculated geometries and energetical parameters for [L(3)ZnOH](+)/CS(2) model systems (L = NH(3), imidazole) are compared with those obtained previously for the CO(2) hy...

Bis(1,3,4-thiadiazolo)-1,3,5-triazinium halides 6 can be easily attacked by nucleophiles at either the C(3a) or the C(4a) position of the central six-membered (cationic) ring. Nucleophilic attack leads to at least two reaction channels, one of which has been previously detected (pathway a) and leads to novel aminals 19. In this paper we report on a...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The diastereomeric 16-bromo- and 16-azido-17-alcohols 5-8, 11, 12, 16, and 17 and 17-ketones 3, 4, 9, and 10 of the 13alpha-estra-1,3, 5(10)-triene series were synthesized as precursors for biologically active compounds and chiral ligands for metal complexation. Conformational investigations of these and some other compounds via X-ray analysis and...

A series of N-alkyl- and N-aryl-2-cyano-2-diazoacetamides was synthesized by the reaction of 2-amino-2-cyanoacetamides with sodium nitrite in hydrochloric acid. The mechanism of their heteroclectrocyclization to 5-hydroxy-1,2,3-triazoles was investigated kinetically and theoretically by the B3LYP/6-31+G* method. The conclusion was made on the basis...

A combination of density functional calculations (B3LYP/6-31+G(d) level of theory) and experimental investigations (NMR and cryoscopic measurements) lead to structural assignments in solution for a series of three sulfur stabilized allyllithium compounds 1−3. All three lithium species are monomers in THF under the experimental conditions studied he...