New N-(Arylsulfonyl)-5-aminomethylbicyclo[2.2.1]hept-2-enes. Synthesis, 1H and 13C NMR Spectra,and Chemical Reactions

A synthesis of new N-(arylsulfonyl)-5-aminomethylbicyclo[2.2.1]hept-2-enes obtained by reaction of stereoisomeric exo- and endo-5-aminomethylbicyclo[2.2.1]hept-2-enes with arylsulfonyl chlorides is described. With the use of the data of ¹H and ¹³C NMR spectra, including those of two-dimensional spectra recorded in COSY and NOESY mode, the contribution of stereochemical features of sulfonamides into the spectra structure of endo- and exo-isomers was evaluated. Applying various methods of the phase-transfer catalysis alkylation and acylation of the stereoisomeric arylsulfonamides containing a norbornene fragment was carried out. The reactions of alkylated stereoisomeric sulfonamides, N-(benzyl)-N-(3,4-dichlorophenylsulfonyl)-5-aminomethylbicyclo[2.2.1]hept-2-enes, with peroxyphthalic acid provide epoxides; the orientation of substituents in the cage norbornene fragment does not affect the direction of the process. The structure of the products obtained by sulfonamides transformations was confirmed by IR, ¹H and ¹³C NMR spectra.     

Thermal rearrangement of 2-oxabicyclo[2.2.2]oct-5-eno-3-carboxylic acids

The decarboxylation of 2-oxabicyclo[2.2.2]oct-5-eno-3,3-dicarboxylic acid, obtained by hydrolysis of the Diels-Alder adduct of diethyl mesoxalate with cyclohexa-1,3-diene, gave two stereoisomeric γ-lactones of 2-hydroxy-1,2,5,6-tetrahydromandelic acid.     

Alkoxy compounds XIX. The stereoisomerism of some 2, 5-dialkyl-5-α-alkoxyethyl-1, 3-dioxanes

Using PMR spectra and GL chromatograms, it is shown that 2,5-di methyl-, 2-isopropyl-5-ethyl-, 2, 5-diisopropyl-5-α-isopropoxyethyl-1, 3-dioxane are mixtures of isomers. Efficient columns are used to fractionate these mixtures into the individual isomers, purities being checked by GLC. From PMR spectra and dipole moments it was concluded that the low-boiling isomers of the stereoisomeric dioxanes are trans forms with chair configuration, while the high-boiling isomers are cis, and have the unsymmetrical boat-shaped configuration.     

Oxidation of stereoisomeric N-amino-11,14-dicyanoperhydroacridines

The oxidation of trans-syn-trans-N-amino-11,14-dicyanoperhydroacridine with manganese dioxide or bromine gives two stereoisomeric 11,12-dicyanoperhydrofluorenes and two stereoisomeric 2-cyano-1-(2-cyanocyclohexylmethyl)-1-cyclohexenes. The oxidation of trans-anti-cis-N-amino- 11,14-dicyanoperhydroacridines with manganese dioxide gives three other stereoisomers of 11,12-dicyanoperhydrofluorene.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 104–108, January, 1976.     

Studies on the formation of [5]metacyclophane

Base induced elimination of HCl from the dichloro[5.3.1]propellane $\text{3a}$ gives a mixture of [5]metacyclophane ($\text{1}$) and tetrahydrocyclopentacyclooctenes ($\text{2}$), while the stereoisomeric $\text{3b}$ affords $\text{1}$ quantitatively.     

Reaction of hydroxylamine with 5-aminooxazoles. A new route to isoxazoles

The nucleophilic attack of hydroxylamine at the 5 position of 2-aryl-4-trifluoroacetyl-5-amino-oxazoles leads to a mixture of stereoisomeric isoxazolines. Dehydration of these isomeric isoxazolines in the presence of trifluoroacetic anhydride gives 3-amino-4-acylamino-5-trifluoromethylisoxazoles. The structures and spectroscopic data of these compounds are discussed.     

Synthesis of stereoisomeric alkyl- and phenyl-substituted 5-cyanopiperidine-3,4-diols

-Hydroxy--[N-(2-cyanoethyl)amino]ketones were obtained by the reaction of methyl- and phenyl-substituted 2-acyloxiranes with 3-alkylaminopropionitriles. Treatment of the products with sodium tert-butoxide gave stereoisomeric 5e-cyanopiperidine-3,4-diols, the three-dimensional structures of which were established by means of spectral data, as well as by means of isomerization and oxidation with periodic acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1207–1211, September, 1986.     

Synthese der vier stereoisomeren Dihydropalustraminsäuren. 13. Mitteilung über Schachtelhalmalkaloide

Syntheses of the four stereoisomeric dihydropalustramic acids ([6-(1-hydroxypropyl)-2-piperidyl]acetic acids) (?)-Dihydropalustramic acid, a key product in the structure elucidation of the alkaloid palustrin, has been assigned the threo-cis structure 20 by comparison with the four stereoisomeric (±)-dihydropalustramic acids (threo-cis, threo-trans, erythro-cis, erythro-trans). The latter were synthesized by a new route to α, α′-di-substituted piperidines of this type. Ring closure to the piperidine ring with simultaneous stereospecific formation of the hydroxylated side chain has been achieved by reaction of the stereoisomeric methylesters of 7,8-epoxy-2-decenoic acids with benzylamine. Assignment of the configuration at the piperidine ring is based on careful comparison of the H-NMR. spectra of the N-benzylpiperidines and with the help of lanthanide shift reagents.     

13C Pulse fourier transform NMR of menthol stereoisomers and related compounds

¹³C NMR spectra of menthol stereoisomers have been determined. The correlations of chemical shifts of these ring carbons with those of stereoisomeric 2-isopropylcyclohexanols are examined. Observed chemical shifts of 1-Me carbons are compared with those predicted from the chemical shifts of stereoisomeric 1-methyl-4-t-butylcyclohexanes. ¹³C NMR spectra of menthyl acetates, and cis and trans p -menthanes have also been examined.     

Azabrendanes V. Synthesis and reactions of stereoisomeric exo- and endo-5-aminomethylbicyclo[2.2.1]hept-2-ene-based ureas

A number of stereoisomeric ureas (N-[aryl(benzyl, or cycloalkyl)carbamoyl]-exo(endo)-5-aminomethylbicyclo[2.2.1]hept-2-enes) have been synthesized from bicyclo[2.2.1]hept-2-en-exo(endo)-5-carbonitrile by reduction with lithium aluminum hydride and subsequent reaction of the resulting amines with aryl (benzyl, or cycloalkyl) isocyanates. Regioselective alkylation of stereoisomeric ureas has been performed with benzyl chloride under liquid/solid phase-transfer catalysis. The outcome of the reactions of ureas with peroxy acids is dependent upon the orientation of substituents in the bicyclic fragment. Exo-isomeric ureas are transformed into corresponding epoxy-derivatives, while reactions of the endo-isomers are accompanied by intramolecular cyclization, resulting in the formation of azatricyclononane derivatives. Quantum-chemical calculations have established a decisive role for additional hydrogen bonding in the stabilization of transition states in these heterocyclization reactions of ureas. The structures and stereochemical homogeneity of the products have been confirmed by the analysis of ¹H and ¹³C NMR spectra and correlation spectroscopy. The mechanism of the intramolecular heterocyclization reaction of ureas and carboxamide of endo-5-aminomethyl-exo-2,3-epoxybicyclo[2.2.1]heptane series has been studied at the BHandHLYP/6-31G(d) level of theory.      

Conformationally constrained dipeptides. Obtention of enantiomerically pure 6‐acetamido‐5‐oxo‐1,2,3,5,6,7‐hexahydro‐3‐indolizine carboxylic acid

The separation of a stereoisomeric mixture of esters 6, and the synthesis of the new enantiomerically pure unsaturated 6,5‐fused bicyclic lactam 2 are described. The key‐step involves trimethylsilyl iodide cleavage, without racemization, of a vinylogous carbamate. The cis N‐ acetylamino acid 2 is a new scaffold for the synthesis of rigid β‐turn mimetics.     

Synthesis and structure of hydrazones obtained from hydrazides of [5-(4-pyridyl)-1,3,4-oxadiazol-2-ylthio]acetic or 2-[5-(4-pyridyl)-1,3,4-oxadiazol-2-ylthio]propionic acids

It has been shown by¹H NMR spectroscopy that hydrazones obtained by the condensation of hydrazides of [5-4-pyridyl)-1,3,4-oxadiazol-2-ylthio] acetic or 2-[5-(2-pyridyl)-1,3,4-oxadiazol-2-ylthio]propionic acids with aldehydes, ketones, and -dicarbonyl compounds exist in DMSO solution as a mixture of stereoisomeric forms.Institute of Chemistry, Vilnius LT-2600, Lithuania. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 966–971, July, 2000.     

Synthesis and Reactions of 4-cis- and 4-trans-Hydroxy-2e-methyl-4-ethynyl-trans-decahydroquinolines

By treating 2e-methyl-4-oxo-trans-decahydroquinoline with lithium acetylide a mixture of stereoisomeric 4-cis-hydroxy-2e-methyl- and 4-trans-hydroxy-2e-methyl-4-ethynyl-trans-decahydroquinolines was obtained in 3:2 ratio. Their reaction with acetonitrile in the presence of sulfuric acid (Ritter's reaction) results in a mixture of stereoisomeric 4-cis-acetylamino-2e-methyl- and 4-trans-acetylamino-2e-methyl-4-ethynyl-trans-decahydroquinolines in the same ratio. The ethynyl group of alcohols synthesized is not hydrated under conditions of Kuchrerov's reaction. The boiling of the alcohols with formic acid furnished a mixture of 4-acetyl-2e-methyl and 2e-methyl-4-ethynyl-1,2,3,6,7,8,9,10-octahydroquinolines in 1:7 ratio. The former of these compounds under conditions of Ritter's reaction yielded a mixture (1:1.4) of stereoisomeric 4-acetyl-4-trans-acetylamino- and 4-acetyl-4-cis-acetylamino-2e-methyl-trans-decahydroquinolines. From 2e-methyl-4-ethynyl-1,2,3,6,7,8,9,10-octahydroquinoline under the same conditions were obtained both already mentioned stereoisomeric 4-acetylamino-2e-methyl-4-ethynyl-decahydroquinolines (53% of cis-isomer and 35% of trans-isomer in the mixture) and 4-acetyl-4-acetylamino-2e-methyldecahydroquinolines (7% of cis-isomer and 5% of trans-isomer).     

Valenzisomerisierung von cis-dienonen IV. Die vier stereoisomeren Formen von 4-Methyl-6-phenyl-3, 5-hexadien-2-on

(Z,Z)-4-Methyl-6-phenyl-3,5-hexadien-2-one ( 5 ) is converted to its (Z,E)-isomer 6 at 35° in the dark. This ready, uncatalysed cis,trans-isomerization is shown to proceed through 2H-pyran 9 . Irradiation of either stereoisomeric dienone 6, 7 or 8 at 0° produces a photostationary mixture of 5, 6, 7 and 8 in which the (Z,Z)-isomer 5 predominates.     

Tartraldehydes 5:1 Syntheses of Chiral Synthetic Building Blocks for Some Intermediates of the Arachidonic Acid Cascade

Abstract

Two enantiomeric 5,6-dihydroxy-7-oxoheptanoates (4ba, 4bb) and three stereoisomeric 2,3-dihydroxyoctanal (5ba, 5bb, 5bc) derivatives have been synthesized in three steps from tartraldehydes 6, 7 and 8.     

Configurational assignment by 13C NMR of stereoisomeric 3-bromo-3-acyl derivatives of 5α- and 5β- androstane

The configurational assignment of stereoisomeric 3-bromo-3-acyl derivatives of steroids in both the 5α and 5β series has been carried out by comparing the ¹³C chemical shifts of C-3. A downfield shift is observed for C-3, bearing a bromine and an acyl group, on going from the isomer with an equatorial bromine to that with an axial bromine. This rule has been established by comparison of the ¹³C chemical shifts of model compounds in 4-tert-butylcyclohexanes of known configuration.     

Conformational analysis of the stereoisomers of 3-methyl-2-oxo-2-thiabicyclo[4.4.0]decane

The conditions for the separation of the stereoisomeric sulfones and sulfoxides of 3-methyl-2-thiabicyclo[4.4.0]decane were found by means of capillary gas-liquid chromatography, and the relative thermodynamic stabilities of the latter were determined. The configuration of the stereoisomeric sulfoxides was established on the basis of oxidation data, the characteristics of the physicochemical properties, and the Kerr effect.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 621–624, May, 1976.     

Konfigurative Zusammenhänge in der Muscarinreihe; Chiralität des epi-, allo- und epiallo-Muscarins,des Muscarons und allo-Muscarons. Zur biogenese des muscarins 37. Mitteilung über muscarin und verwandte stoffe

The chirality of all stereoisomeric muscarines has been determined. (–)-Muscarine chloride was converted to (+)-normuscarine, which in turn was oxidized to (+)-normuscarone. Epimerisation by acid catalysis of the latter gave a mixture of the C(2)-epimers, namely (+)-normuscarone and (–)-allo-normuscarone. From these were prepared by reduction with LiAlH₄ optically active stereoisomeric noralcohols. The natural stereoisomeric muscarines so far isolated are: (+)-(2S, 3R, 5S)-muscarine, (–)-(2S, 3R, 5R)-allo-muscarine and (+)-(2S, 3S, 5S)-epi-muscarine. Identical chirality appears only at C(2). This fact has to be taken into consideration for further speculations about the biogenesis of muscarines. Optically active muscarone and normuscarone exhibit a strong Cotton effect at 300 nm, which is interpreted in terms of absolute configuration by analogy to optically active substituted cyclopentanones. Optically active allo-normuscarone exhibits a very weak Cotton effect only, presumably because of predominant pseudo-rotation. The relative stability of the stereoisomeric norketones has been determined. Normuscarone (cis-2,5) is by 0,39 kcal/mol more stable than allo-normuscarone (trans-2,5).     

Epoxy derivatives of {(5-[(1-Phenylethyl)aminocarbonyl]-cyclopent-2-en-1-yl}methyl acetates

Diastereoisomeric [(1R,5S)-5-“[(1R)-1-phenylethyl]aminocarbonyl”cyclopent-2-en-1-yl]methyl acetate and [(1S,5R)-5-“[(1R)-1-phenylethyl]aminocarbonyl”cyclopent-2-en-1-yl]methyl acetate reacted with m-chloroperoxybenzoic acid to give the corresponding stereoisomeric α- and β-epoxy derivatives, which were identified on the basis of their spectral parameters.     

Mannich reaction in a number of six-membered heterocyclic γ,-ketones. X. Stereochemistry of the reduction and phenylation of 2, 2-dimethyl-5-dimethylaminomethyl-4-oxotetrahydropyran

2, 2-Dimethyl-5-dimethylaminomethyl-4-oxotetrahydropyran was subjected to reduction with lithium aluminum hydride, sodium borohydride, aluminum isopropoxide, and lithium in liquid ammonia, to catalytic hydrogenation over Raney nickel, and phenylation with phenyllithium. The quantitative ratios in the resulting mixtures of stereoisomeric 2, 2-dimethyl-5-dimethylaminomethyl-4-hydroxytetrahydropyrans and their dependence on the character of the reducing agents were established by means of gas — liquid chromatography and PMR spectroscopy. The individual geometrical isomers of the amino alcohols were isolated, and their three-dimensional structures were studied by means of their PMR and IR spectra.See [1] for communication IX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 611–616, May, 1976.