bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elektrochemische Oxydation organischer Verbindungen in Fluorsulfonsäure. I. Voltammetrische Untersuchung von Arylsulfonylfluoriden
Authors: Rudenko A. P. , Sarubin M. Ja. , Pragst F. 
Published: December 2004

Electrochemical Oxidation of Organic Compounds in Fluorosulfuric Acid. I. Voltammetric Investigation of ArylsulfofluoridesThe electrochemical oxidation of phenylsulfonylfluoride 1g and 16 of its alkylsubstituted derivates 1a–1g as well as a series of monomeric and dimeric products of the chemical oxidation of 1 were investigated by cyclic voltammetry in fluorosulfuric acid at –76°C. In all cases cation radicals could be detected as primary oxidation products. In further reaction steps one or two meta‐ or ortho‐methyl groups are converted into fluorosulfonyloxymethyl groups. Depending on the stability of the cation radicals this process occurs either through an EEC‐mechanism via the intermediate formation of dications (penta‐ and tetramethylsubstituted compounds) or through an ECE‐mechanism with rate determining deprotonation of the cation radical.
Synthese eines geschützten cyclischen Disulfidoktapeptides A6–13 der (Ala12)‐Schafinsulin‐A‐Kette
Authors: Kaufmann Klaus‐Dieter , Nieke Eva‐Maria 
Published: December 2004

Synthesis of a Protected Cyclic Disulphide Octapeptide A6‐13 of the (Ala12)‐Sheep Insulin‐A‐ChainThe synthesis of a protected (Ala12)‐sheep insulin‐A‐chain octapeptide with a 6,11‐disulphide ring using the combination of A6,11‐S‐trityl/A 7‐S‐diphenylmethyl thiol protecting groups is described. For the formation of the cyclic disulphide octapeptide 2 the linear octapeptide, Boc‐Cys(Trt)Cys(Dpm)AlaGlyValCys(Trt)Ala‐Leu‐OH (1), is prepared by a 4 + 4‐ as well as a 3 + 2 + 3‐fragment condensation scheme followed by treatment with iodine in methanol. Most of the peptide coupling reactions were performed using the azide technique obtaining the intermediate peptide fragments in good yields. For the characterization of the cyclic disulphide peptide 2 the 13C‐n.m.r.‐spectroscopy was used in combination with other usual methods.
Chemische Synthese des Pentadecadesoxyribonucleotides d(TTCTTCTA CACACCC) nach der verbesserten Triester‐methode
Authors: Rosenthal A. , Cech D. , Veiko V. P. , Shabarova Z. A. , Orezkaja T. S. 
Published: December 2004

Chemical Synthesis of the Pentadecadeoxyribonucleotide d(TTCTTCTACACACCC) by Improved Triester ApproachThe chemical synthesis of the pentadecanucleotide d(TTCTTCTACACACCC) by improved triester approach in solution with TPS/1‐Methylimidazole as condensation agent is reported. Almost all condensation were complete within 5‐‐10 minutes giving yields over 80%. All intermediate triester blocks showed purity degrees of higher than 90% after purification by simple silicagel chromatography. After deblocking the pentadecanucleotide was purified by DEAE‐cellulose 52 chromatography and desalted, then showing 100% purity as seen by 20% polyacrylamide gel electrophoresis of the 5′‐32P labeled oligonucleotide. The sequence of the synthetic oligomer was determined and confirmed by using the two‐dimensional mobility shift method. The pentadecanucleotide was used as hybridisation probe for cloned human insulin c‐DNA.
Synthese und Eigenschaften von Trimethincyaninen mit verbrückten Ketten
Authors: Fanghänel E. , Behrmann K. , Bach G. 
Published: December 2004

Synthesis and Properties of Trimethinecyanines with Bridged ChainsThe effects of meso‐substituents (H, morpholino, ethoxy) and hydrocarbon bridges, on the light absorption and the electrochemical properties of trimethinecyanine dyes (4a‐‐f, 8a–c 10a–f) are investigated. The results are in a good agreement with the predictions of the perturbation theory. Methods for the preparation of the dyes involving reaction of methylthio quaternary salts (1a, b) with enamines (2a, b) are described.
Synthese des 2‐Desalkyl‐cyclols vom Ergotamintyp
Authors: Losse G. , Schumann G. 
Published: December 2004

The Synthesis of the 2‐Desalkylcyclol of the Ergotamine‐TyperBenzyloxycarbonyl‐S‐seryl‐S‐phenylalanyl‐S‐proline‐p‐nitrophenylester is synthesized by an improved route and oxidized by lead‐tetraacetate to a mixture of the two diastereomeric (RSS, SSS) benzyloxycarbonyl‐hydroxyglycyl‐phenylalanyl‐proline‐p‐nitrophenyl‐esters. Treatment of this mixture with an aqueous potassium tartrate solution provides two epimeric cyclols (2‐benzyloxycarbonylamino‐5‐benzyl‐10b‐hydroxy‐3,6‐dioxo‐octahydro‐8H‐oxazolo[3,2‐a]‐pyrrolo‐[2,1‐c]‐pyrazines), which are separated into the aci‐form as well as into the natural form corresponding to the 2R:5S:10aS:10bS configuration of ergotamine.
Nucleophile Substitution in der 1,3,5‐Triazinreihe. IX. Kinetik und Mechanismus der Reaktion von Cyanurchlorid mit 4′‐substituierten 4‐Aminoazobenzenen
Authors: Havlik I. , Bacaloglu R. 
Published: December 2004

Nucleophilic Substitutions in 1,3,5‐Triazines. VII. The Kinetic and ¦ Mechanism of Cyanuric Chloride with 4′‐Substituted 4‐AminoazobenzensThe kinetic and mechanism of cyanuric chloride reaction with 4′‐substituted 4‐aminoazobenzens in dioxan‐water was studied by conductometry. An addition‐elimination mechanism with a monomolecular elimination of chlorine ion at low water concentrations or a nucleophilic attack of 4‐aminoazobenzens at high water concentration as low step has been supported by experimental data.
Untersuchungen zum photochemischen Ausbleichverhalten von tautomeriefähigen Azofarbstoffen. V. Oxidation substituierter 1‐Phenylazo‐2‐naphthole durch Singulettsauerstoff in polymerer Matrix
Authors: Haessner R. , Mustroph H. , Epperlein J. 
Published: December 2004

Studies on Photo Fading of Tautomeric Azo Dyes. V. Oxydation of Substituted 1‐Phenylazo‐2‐naphtholes by Singlet Oxygen in a Polymeric MatrixThe logarithms of rate constants of methylene blue sensitized photolysis of substituted 1‐phenylazo‐2‐naphthols (1a–y) in polymer matrix show no linear correlationship with respect to Hammett‐δ‐constants of the substituents.The slope of the function lg k = f(δ), where k represents rate constants, differs for positive and negative δ‐values in sign but decomposition is oxydative at all substituents. It is possible to explain the nonlinear correlation, when singlet oxygen 1O2 attacks only the anti‐hydrazone‐tautomer in the dyes investigated.
Elektrophile Reaktionen an der Maleinimiddoppelbindung
Authors: Augustin M. , Köhler M. 
Published: December 2004

Electrophilic Reactions on the Maleimide Double BondThe aminosubstituted maleimides 1 are deprotonated to the anions 2, which are reacted with various electrophiles. By this way with heterocumulenes, acid chlorides and vinylogous acid chlorides the new acylated maleimides 3–6, 9, 10 are isolated. This reaction presents a method of direct acylation on the maleimide double bond.
Desaktivierungsverhalten von Arenen und Heteroarenen. XL. Mechanismus der reversiblen intramolekularen [π4s + π4s]‐Photocycloaddition von α, ω‐Bis‐(9‐acridiziniumyl)‐alkanen
Authors: Wagner J. , Bendig J. , Kreysig D. 
Published: December 2004

Deactivation Behaviour of Arenes and Heteroarenes. XL. The Mechanism of the Reversible Intramolecular [π4s + π4s]‐Photocycloaddition Reaction of α,ω‐Bis‐(9‐acridiziniumyl)‐alkanes.On electronic excitation the bichromophores deactivate by fluorescence and radiationless photophysical processes from its local excited state. Simultaneously, intramolecular interaction occurs between the excited chromophor and that in the ground state (i.e. by reversible energy migration or intramolecular excimer formation). The excimer rapidly collapses to the cyclomer assuming a common pericyclic transition state for the reversible photocycloaddition. In the pericyclic state the reaction is split into cyclomer formation or backformation of bichromophores in the ground state, respectively. This mechanism of the reversible intramolecular [π4s + π4s]‐ photo‐cycloaddition reaction is discussed on the basis of a potential correlation diagram.
Untersuchungen zum photochemischen Ausbleichverhalten von tautomeriefähigen Azofarbstoffen. VI. Zur photochemischen Oxydation von Phenylazo‐acetylacetonen und Phenylazopyrazolonen durch Singulettsauerstoff
Authors: Mustroph H. , Potocnak J. , Grossmann N. 
Published: December 2004

Investigations of the Photo‐Fading of Tautomeric Azo Dyes. VI. The Photochemical Oxidation by Singlet Oxygen of Phenylazoacetylacetones and PhenylazopyrazolonesThe dye‐sensitized photo‐oxidation by singlet oxygen of phenylazoacetylacetones (1) and Phenylazopyrazolones (2) has been investigated. The photo‐fading of dyes is accelerated in the presence of Methylene Blue, a sensitizer of singlet oxygen, in airsatured methanolAn excellent relationship exists between the fading‐rate of a series of dyes (1) and Hammett‐σ‐constants. An unexpected trend was found for photo‐fading of a series of dyes (2). The Hammett plot consists of two parts, with a negative slope derived from electron‐releasing substituents and a positive slope derived from electron‐withdrawing substituents. The anomalous photo‐fading is due to an attack of singlet oxygen on the more reactive anion of the phenylazopyrazolones in the case of electron‐withdrawing substituents. In methanol containing acetic acid the dyes (2) exist only as the hydrazone tautomers. Under these conditions the fading‐rate show a linear relationship with σ‐constants.
EPR‐Untersuchungen zur Photolyse halogenierter organischer Verbindungen. II. CHBr3 und CBr4 in glasartigen und polykristallinen Matrices
Authors: Stösser R. , Pritze B. , Abraham W. , Dreher B. , Kreysig D. 
Published: December 2004

EPR‐Investigations on the Photolysis of Halogenated Organic Compounds. II. CHBr3 and CBr4 in Glassy and Polycrystalline MatricesPhotolysis of CHBr3, CDBr3 and CBr4 in glassy and polycrystalline matrices (alcohols, diethylether, benzene derivatives and KBr) at T ≥ 77 K yields stationary e.p.r.‐spectra in the range of effective g‐factor from 2.2 to 1.9. By comparison of the spectra of CHBr3 and CDBr3, exposed to γ‐rays and u.v. light respectively, and the spectra of these compounds in matrices it was shown that the photolysis in matrices produces the species \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CBr}_4\,^{_{\bar.}} $\end{document}, ·CBr3 and α‐Br‐radicals from the halogenated compounds and HĊO, ·CH3, CH3ĊHOH, RĊHOH, and ·C2H5 from the matrix. Photolysis of halogenated compounds in CH3OH and CD3OD yields only HĊO and ·CH3 together with a very small amount of bromine‐containing radicals. In all other investigated matrices the concentration of bromine containing species is controlled by physical and chemical properties of the matrix. Time development of the \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CBr}_4\,^{_{\bar.}} $\end{document}‐radical and of those generated from the matrix is different and gives insight into the complex photoreaction in solid matrices.
β‐Thiocyanatovinylcarbonylverbindungen. XI. Ungewöhnliche Substituenteneffekte bei der massenspektrometrischen Fragmentierung von β‐Thiocyanatovinylaldehyden
Authors: Herzschuh R. , Schulze B. , Mühlstädt M. 
Published: December 2004

β‐Thiocyanatovinylcarbonyl Compounds. XI. Unusual Substituent Effects in the Mass‐spectrometrical Fragmentation of β‐ThiocyanatovinylaldehydesThe mass spectra of homologous Z/E‐isomers and constitutional isomers of β‐thiocyanatovinylaldehydes are discussed. The main fragmentation consisting of HCN‐loss from the molecular ion is influenced by the substituents so that the constitutional and steric isomers can be clearly distinguished by the \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm M - HC}\left. {\overline {\, {\rm N} \,}}\! \right| + /{\rm M + }^ \cdot $\end{document} ratio. Alkyl homologues with a hydrogen atom in γ‐position to the aldehyde group show an unusual intensive CN‐radical loss due to a „hidden hydrogen rearrangement”︁, which was proved by deuteration experiments.
1H‐, 13C‐ und 15N‐NMR‐Untersuchungen zur Tautomerie von Bispyrazolonen vom Typ der 4,4′‐Methyliden‐bis‐(3‐stearoylamino‐1‐phenyl‐pyrazolin‐5‐one)
Authors: Mistol J. , Grossmann N. , Pietsch H. , Fanghänel E. 
Published: December 2004

1H‐N.M.R., 13C‐N.M.R., and 15N‐N.M.R.‐Investigations Concerning Tautomerism of Bispyrazolons of 4,4′‐Methyliden‐bis‐(3‐stearoylamino‐1‐phenyl‐pyrazolin‐5‐on) TypeWith the help of 1H, 13C and 15N chemical shifts of the n.m.r. signals of the structure elements OH, NHCO, 13C‐5, 15N‐1, 15N‐2 and 15N‐2‐H and using the coupling constants nJ(15NH) and nJ(13C15N) (n = 1, 2) of the doubly 15N labelled bispyrazolone 1, a chelated and an associated species were shown to exist in the slightly polar solvent CDCl3. The chelated bispyrazolone (BC)ch contains one pyrazolone ring in the tautomeric NH form B and the other in the tautomeric OH form C. In the associated bispyrazolone (BB)as, both pyrazolone rings exist in the NH form B. Observation of the time, concentration and temperature dependence of the n.m.r. spectra of 1 resulted in the detection of complex exchange processes in tautomeric equilibrium. Apart from the intermolecular exchange process (BC)ch ⇌ (BB)as, another exchange process (BC)ch ⇌ (CB)ch occurs, with intermolecular interactions being involved. It has been established that in the case of substitution in the methylidene bridge (2, 3) the lefthand side of the equilibrium (BC)ch ⇌ (BB)as participates in the process to a greater extent than in the case of 1 (unsubstituted methylidene bridge).
Durch bisquartäre Ammoniumsalze katalysierte Zweiphasenreaktion von 1‐Bromoctan mit Natriumacetat und Kaliumacetat
Authors: Schiefer H. , Beger J. , Lorenz U. 
Published: December 2004

Two‐Phase Reaction of 1‐Bromooctane with Sodium Acetate and Potassium Acetate Catalyzed by Diquaternary Ammonium SaltsNew unsaturated diquaternary ammonium salts (diquats) were prepared in two ways from ditertiary amines 3 and 1‐bromoalkanes or from 1, 4‐dibromobut‐2t‐ene and tertiary monoamines. A comparison of their catalytic ability with that of saturated diquats and with that of corresponding monoquats was made. The reaction of n‐C8H17Br with NaOAc or KOAc in the two‐phase system liquid‐liquid without an additional solvent is catalyzed more effectively by the unsaturated diquats than by the saturated diquats and the monoquats. Most of the used quats catalyze the ester formation from NaOAc more effectively in the system liquid‐liquid, however, the ester formation from KOAc more effectively in the system solid‐liquid; KOAc is generally superior to NaOAc in both systems. Consequently, in the phase‐transfer catalyzed ester formation from alkali acetate and alkyl halides not only the structure of the quat but also the inorganic cation of the acetate have influence on the rate of conversion.
Derivatisierung von Aminen mit 4‐substituierten 7‐Nitrobenz‐2,1,3‐oxadiazolen
Authors: Heberer H. , Kersting H. , Matschiner H. 
Published: December 2004

Derivatization of Amines with 4‐Substitured 7‐NitrobenzofurazansElectrophilc derivatives of 4‐nitro‐benzofurazan with different reactivities were used to synthesize 28 new mono‐ and disubstituted 4‐amino‐7‐nitrobenzofurazans 2b, 2d, 2f–2i, 2l, 2m–2n, 3b–3f, 3h–3j, 4e–4d, 4f–4k, 4m, 4o–4p. A reaction mechanism is proposed on the basis of the differences of the reactivities and a preliminary kinetic examination. The acid character of the NH‐function in monosubstituted compounds is demonstrated by means of spectroscopical investigation of pKa‐values.Data from i.r., u. v./vis, and fluorescence studies are offered.
Synthese von substituierten 5‐Amino‐1,2,4‐triazolen
Authors: Evers R. , Fischer E. 
Published: December 2004

Synthesis of Substituted 5‐Amino‐1,2,4‐triazolesN‐Nitro‐amidino‐dithiocarbimidic acid dimethylester 1 reacts with monosubstituted hydrazines under formation of the substituted 5‐amino‐1, 2, 4‐triazoles. Disubstituted hydrazines give under the same conditions N‐nitro‐amidino‐S‐methyl‐isothiosemicarbazides.The reaction of some more hydrazine derivatives with 1 yields the adequate substituted 1, 2, 4‐triazoles.
Aufklärung der Molekülstruktur von Rohölinhaltsstoffen durch NMR‐Spektroskopie. IV. Strukturtypen‐ und Strukturgruppenanalyse von Erdölfraktionen durch 1H‐NMR‐Spektroskopie
Authors: Deutsch K. 
Published: December 2004

Elucidation of the Molecular Structure of Petroleum Constituents by N.M.R. Spectroscopy. IV. Analysis of Petroleum Fractions with Respect to Types of Structure and Structural Groups by 1H N.M.R. SpectroscopyAn improved method is presented which permits a quantitative analysis of crude oil products with a final boiling point below 400°C by means of the data of the 1H n.m.r. spectrum and the average boiling point of the petroleum fractions. The types of aromatic structures are distinguished with respect to mono‐, bi‐, and tricyclic aromatics, and additionally, further structural group information is obtained.
Cyclisierungsreaktionen β,γ‐ungesättigter Kohlensäurederivate. XI [1] Untersuchungen zur Stereochemie der Cyclofunktionalisierung β,γ‐ungesättigter Carbamidsäureester
Authors: Mühlstädt M. , Meusinger R. , Olk B. , Weber L. , Widera R. 
Published: December 2004

Cyclization Reactions of β,γ‐Unsaturated Derivatives of Carbonic Acid. XI. Investigation of Stereochemistry of the Cyclofunctionalization of β,γ‐Unsaturated Carbamic Acid EstersN, N‐Disubstituted β,γ‐unsaturated urethanes 1 have been cyclized to 3,5‐disubstituted oxazolidine‐2‐ones 3 by aromatic sulfenyl chlorides 2. The stereochemistry of the products and the cyclofunctionalization reaction were investigated.
On the Structure of Carbamoylated 2‐Phenylaminopyridines
Authors: Mørkved Eva H. 
Published: December 2004

AbstractUnambiguous preparations of 2‐(N‐alkoxycarbonyl‐N‐phenyl)aminopyridine 1‐oxides are used to prove that the product from 2‐phenylaminopyridine 3 and phenyl isocyanate is the expected urea 2a. Recently a 1,2‐dihydropyridine derivative 1 [4] has been claimed to be the product from 3 and phenyl isocyanate. The exocyclic nitrogen of 3 invariably reacts as the nucleophile towards electrophiles such as carbonyl chloride, esters of chloromethanoic acid and aryl isocyanates. 1H n.m.r. and 13C n.m.r. spectra support the assigned structures of the products from these ractions.
Prostaglandins and Prostaglandin Intermediates. XVII [1]. Synthesis of the Main Metabolite of the PGF2α Analogue Cloprostenol
Authors: Theil Fritz , Costisella Burkhard , Mahrwald Rainer , Gross Hans , Schick Hans , Schwarz Sigfrid 
Published: December 2004

AbstractThe δ‐lactone 5, the main metabolite of the PGF2α analogue cloprostenol, is prepared in four steps from the homologous γ‐lactone 1 in an overall yield of 42% by conversion into the γ‐lactol 3, which is olefinated with diethyl 1‐cyano‐1‐dimethylamino‐methylphosphonate to the cyano enamine 4 and finally hydrolyzed under various conditions. The described reaction sequence represents an example for the general possibility of the ring enlargement of γ‐lactones to δ‐lactones.
Untersuchungen zu den Sondeneigenschaften von 7‐Hydroxy‐cumarinen in micellarer Cetyl‐triethyl‐ammoniumbromid‐Lösung – Hilfsmittel zur Beschreibung von micellaren Systemen
Authors: Knoll H. , Seidel A. , Hennig H. , Soboleva I. , Zaitzev N. , Kuzmin M. G. 
Published: December 2004

Investigation on Probe Properties of 7‐Hydroxy‐coumarines in Micellar Cetyl‐triethyl‐ammoniumbromide Solution – Means for Characterization of Micellar SystemsAnions of 3‐substituted 7‐hydroxy‐coumarines (1a–c) as fluorescence probes have been studied in this work. Acid‐base equilibria in water and micellar solution of cetyl‐triethylammoniumbromide (cmc = 0,72 mmol l−1), fluorescence properties and fluorescence quenching by octacyano‐molybdate‐IV have been investigated. It has been confirmed that probe and quencher are completely micellized. Fluorescence life times and quenching constants per one quencher molecule in the micell of about 108 s−1 have been determined. The kinetics of saponification of the probe 3‐acetyl‐7‐hydroxy‐coumarine at pH = 12 in micellar solution has been followed by probe fluorescence.
Zur Chemie der 5‐Amino‐2‐phenyl‐1,2,3‐thiadiazoliumsalze
Authors: Gewald K. , Calderon O. , Hain U. 
Published: December 2004

On the Chemistry of 5‐Amino‐2‐phenyl‐1,2,3‐thiadiazolium SaltsTreatment of the title compounds 1 with pyridine yield the phenylhydrazones of the 1,2,4‐thiadiazol‐3,5‐diyl‐glyoxylic acid derivatives 4. The amides 4a, b can also be obtained by reaction of the phenylhydrazono cyanacetoamides 3a, b with sulphur in the presence of pyridine. Nitriles react with 1 to form the phenylhydrazones of the 1,2,4‐thiadiazol‐5‐yl‐glyoxylic acid derivatives 6. Reduction of 6a yields the 1,2,4‐thiadiazol‐5‐yl‐glycine derivative 7. Depending on its condition the reaction of 1c with benzoyl acetonitrile yield either the 1,2,4‐thiadiazole or the 4‐amino‐thiazole derivative (6i or 8). From 1a and ethyl acetoacetate the phenylhydrazone of the thiazol‐2‐yl‐glyoxylic acid derivative 9 arises which can be reduced to yield the thiazol‐2‐yl‐glycine derivative 10. The addition of 1 onto isothiocyanates in the presence of pyridine yields the substituted N‐(1,2,3‐thiadiazol‐5‐ylidene)‐thioureas 12a, b. Carboxylic acids react with 1 in the presence of pyridine to form the 5‐Acylimino‐1,2,3‐Δ3‐thiadiazolines 13.
Ein einfacher Weg zu neuartigen Borhaltigen Spiroverbindungen
Authors: Hartmann H. 
Published: December 2004

A Simple Route to a New Type of Boron‐containing SpirocompoundsThe reaction of enolizable 1,3‐dicarbonyl compounds 6 with diol compounds 5 and boric acid results in a new typ of boron‐containing spiro‐compounds 10. By using different substituted 5 and 6 more than 40 new spiroboronates 10 have been prepared and characterized by means of spectroscopic and analytical data.
Intermediates of Prostanoid Synthesis. Stereospecific conversion of (+)‐5β‐hydroxycyclopenten‐2‐yl‐1β‐acetic acid γ‐lactone into (+)‐1β‐methoxycarbonylmethyl‐2β,3β‐(p‐nitrobenzylidene)‐dioxycyclopentan‐5‐one
Authors: Freimanis J. , Gerca L. , Turovskis I. , Liepinš E. , Lola D. , Mishnev A. , Bundule M. , Bleidelis J. 
Published: December 2004

AbstractStarting from (+)‐5β‐hydroxycyclopenten‐2‐yl‐1β‐acetic acid γ‐lactone (1), (+)‐1β‐methoxycarbonylmethyl‐2β, 3β‐(p‐nitrobenzylidene)‐dioxycyclopentan‐5‐one (7) was prepared within 4 steps. Subsequent cleavage of the latter gives (−)‐3β‐hydroxy‐1‐methoxy‐carbonylmethylcyclopent‐1‐en‐5‐one (8a). Hydroxylation of the lactone (1) was found to give (+)‐2β,3β,5β‐trihydroxycyclopentyl‐1β‐acetic acid γ‐lactone (2a) with cis‐oriented hydroxy groups in respect to the lactone ring. No formation of the trans‐isomer, as has been reported earlier [4], was observed.
Synthesis of Some Pyrazolo‐Anisylethylamine Alkaloids amino acids and related compounds
Authors: Hamama W. S. , Hammouda M. , Afsah E. M. 
Published: December 2004

AbstractSchmidt reaction of the pyrazolo‐β‐(p‐anisyl)‐propionic acid 3 gave the pyrazolo‐anisylethylamine 4. The related alkaloids 5 and 6 were obtained via double Mannich reaction of 4 with the bis‐Mannich base of cyclopentanone and transamination with gramine respectively. The pyrazolo‐phenylalanine 9 was obtained from the EAA adduct 7, through its Schmidt reaction to give 8 followed by hydrolysis, whereas the pyrazolo‐amino acid 12 resulted from the hydrolysis of the corresponding lactam 11.