Determination of the enantiomeric purity of oxfenicine by high-performance liquid chromatography

Summary Reaction of the methyl esters of the -amino acids, R-(–)-, and S-(+)-4-hydroxyphenylglycine (oxfenicine) with the enantiomerically pure acid anhydride of R-(+)-1-methoxy-1-trifluoromethyl-phenylacetic acid (i.e. R-(+)-MTPA) yields diastereoisomeric amides which are separable by high-performance liquid chromatography (HPLC). The ratios of the diastereoisomeric amides may be measured chromatographically and are shown to correspond to the enantiomeric purities of the amino acids. This method is particularly well suited for detecting low levels of an enantiomeric impurity in -amino acids which possess a base labile -methine hydrogen atom.     

Synthesis of Amides of 3-O-Acetyl-18-βH-glycyrrhetic Acid

Methods of preparing amides of 3-O-acetyl-18-H-glycyrrhetic acid from certain amines are described. The structures of the prepared amides have been confirmed by chemical and spectral analyses     

[3 + 3] Cyclocondensation of 1-alkyl-3,4-dihydroisoquinolines with β-keto esters. New annelation reaction in a series of cyclic Schiff’s bases

A new annelation reaction in a series of cyclic Schiffs bases is described with examples of [3 + 3] cyclocondensation of 1-alkyl-3,4-dihydroquinolines and acetoacetic esters.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1492–1500, October, 2004.     

Binding energies of metal monocations to Β-lactones and Β-lactams. A theoretical study of cyclization effects

Ab initio calculations have been performed to study the association of-propiolactam and-propiolactone and their aliphatic analoguesN-methyl acetamide and methyl acetate with different metal monocations: Li⁺, Na⁺, Mg⁺, and Al⁺, in an effort to investigate cyclization effects on the gas-phase basicities of amides and esters, when the reference acid is not a proton. Similarly to what was found for protonation,N-methyl acetamide and-propiolactam are more basic than methyl acetate and-propiolactone, when the reference acids are the aforementioned metal monocations. However, cyclization effects on the corresponding binding energies for both kind of compounds do not parallel those observed for protonation energies, and-lactone is as basic as methyl acetate when the reference acid is Li⁺ and slightly more basic than methyl acetate when the attaching ion is Na⁺. This implies that when the interactions of the bases with the reference acids are essentially electrostatic the reactivity patterns change with respect to those observed when the interactions are essentially covalent.     

Sulfur-containing carboxylic acids. 5. Synthesis and structure of dialkyl sulfides and dialkyl sulfoxides with vicinal carboxyl or acylamino groups

Bifunctional sulfides and sulfoxides containing carboxy, carbamoyl, or acylamino groups in the -position are synthesized, and their IR spectra were studied. An unusual decrease in the frequencies of the carbonyl vibrations (by 20–34 cm^–1) was found for thiodipropionic acid, its amides, and bis(-acylaminoethyl) sulfides by comparison with the corresponding sulfoxides. The low-frequency shift of the CO band in these carbonylsulfides was not, as expected, associated with the intramolecular S...O coordination, since the x-ray structural investigation of thiodipropionic acid and bis(2-trifluoroacetylaminoethyl) sulfide did not show short intra- and intermolecular contacts involving the sulfur atom. Both structures contain intermolecular hydrogen bonds (C=O...HO or C=O...HN).For previous communication, see [1].A. N. Nesmeyanov Institute of Heteroorganic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1766–1775, August, 1992.     

5-Substituted (5S)-imidazolidin-4-ones as effective chiral auxiliary for hydrogenation of α-keto amides

Summary The title chiral auxiliary was used for asymmetric catalytic hydrogenation of amides derived from phenylglyoxylic acid to give mandelamides with high diastereoselectivity (diastereoisomeric excess, d. e. up to 96%).

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5-Substituierte (5S)-Imidazolidin-4-one als effektive chirale Hilfssubstanzen bei der Hydrierung von -Ketoamiden

Zusammenfassung Die asymmetrische katalytische Hydrierung von Phenylglyoxalsäureamiden liefert bei Verwendung der im Titel genannten chiralen Hilfssubstanz Mandelsäureamide mit hoher Diastereoselektivität (diastereomerer Überschuß, d. e. bis zu 96%).

     

New dithio-bis-(diaroylmethanes) and acetyl diaroylchloromethyl disulfides: Attractive synthons and precursors for the liberation of highly reactive dithiiranes or thiosulfines

Summary In a new, feasible procedure five symmetricalpara-substituted diaroylmethanes ((4-X-C₆H₄-CO)₂-CH₂;X=F, Cl, Br, CH₃, and CH₃O) are prepared, in most cases in very good yields. For purification and activation, they are converted into the copper(II) complexes of their enolates. Subsequently, three reaction steps with disulfur dichloride (S₂Cl₂), chlorine, and ethanethioic acid yield new CH-acidic dithio-bis-(diaroylmethanes), -chlorosulfenic acid chlorides, and acetyl diaroyl-chloromethyl disulfides. The latter compounds are of interest for the liberation of highly reactive dithiirane/thiosulfine species. With thiomorpholine, -chlorosulfenic acid chlorides give -chlorosulfenic acid amides.

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Neue Dithio-bis-(diaroylmethane) und Acetyl-diaroylchlormethyl-disulfide: attraktive Synthone und Vorläufer zur Freisetzung hochreaktiver Dithiirane oder Thiosulfine

Zusammenfassung In einem neuen, gut handhabbaren Verfahren werden in meist sehr guter Ausbeute fünf symmetrischepara-substituierte Diaroylmethane ((4-X-C₆H₄-CO)₂-CH₂;X=F, Cl, Br, CH₃ und CH₃O) und daraus zur Reinigung und Aktivierung die Kupfer(II)komplexe ihrer Enolate dargestellt. Drei Reaktionsschritte mit Dischwefeldichlorid (S₂Cl₂), Chlor und Thioessigsäure führen der Reihe nach anschließend zu neuen CH-aciden Dithio-bis-(diaroylmethanen), -Chlorsulfensäure-chloriden und Acetyl-diaroylchlormethyl-disulfiden. Die letzteren Verbindungen sind zur Freisetzung von hochreaktiven Dithiiran/Thiosulfin-Spezies von Interesse. Mit Thiomorpholin geben -Chlorsulfensäurechloride -Chlorsulfensäureamide.

     

Ein einfacher Zugang zu (R)-γ-Amino-β-hydroxybuttersäure (GABOB) aus natürlichem (2S, 4R)-4-Hydroxyprolin

The oxidative decarboxylation sequence (1a 2a 3a 4a 5a) affording -aminobutanoic acid (5a) is adapted to the synthesis of its hydroxy derivative5b. A facile high yield conversion of (2S, 4R)-4-hydroxyproline-methylester-hydrochloride (7) to (R)-GABOB (5b) on a preparative scale is reported with the hydroxypyrrolidone8 as the intermediate.

     

Synthesis and functionalization oftrans-2-(2′-aminocyclohexyloxy)-andtrans-2-(2′-azidocyclohexyloxy)acetic acid

Summary Synthesis of the hydrochloride oftrans-2-(2-aminocyclohexyloxy)acetic acid (4) fromtrans-2-(2-azidocyclohexyloxy)acetic acid (1) is described.4 was acylated at the amino group to give compounds5–8.1 was converted into acid chloride (9) and amides10–13.

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Synthese und Funktionalisierung dertrans-2-(2-Aminocyclohexyloxy)- undtrans-2-(2-Azidocyclohexyloxy)essigsäure

Zusammenfassung Die Synthese destrans-2-(2-Aminocyclohexyloxy)essigsäurehydrochlorids (4), ausgehend vontrans-2-(2-Azidocyclohexyloxy)essigsäure (1), wird beschrieben.4 wurde durch Acylierung der Aminogruppe in die Verbindungen5–8 übergeführt.1 wurde in das Säurechlorid9 und die Carbonsäureamide10–13 umgewandelt.

     

Reaction mechanisms in peptide synthesis. Part 2. Tautomerism of the peptide bond

Summary We had concluded in previous work that ring opening of a 2-alkyl-5(4H)-oxazolone by water or ammonia leads to transient high-energy imidol intermediates which instantly tautomerize to the native amides. Using the MOPAC molecular orbital program, detailed geometric and energetic characteristics of the tautomerism of a peptide bond have been determined on the AM1 level. The results demonstrate that tautomerism of a peptide bond comprises a three-stage process involving three successive transition states and a bimolecular mechanism: (i) EZ peptide bond isomerization followed by dimerization, (ii) concerted double-hydrogen exchange leading to an -hydroxyimine (imidic acid) followed by splitting of the dimer, and (iii) ZE N-methylimine inversion. While pathway (iiiiii) is predicted as a feasible route terminating in the formation of a peptide bond, the inverse route (iiiiii) is excluded as a possible initial step in the generation of a 5(4H)-oxazolone intermediate.     

Interaction of fluorine-containing 1,3-dicarbonyl compounds with polyamines

In the reaction of fluorinated copper(II) 1,3-diketonates with diethylenetriamine (or triethylenetetramine) in CHCl₃, N,N-bis(1,3-aminovinylketones) are formed in 21–35% yields. Fluorine-containing 1,3-diketones and 1,3-ketoesters, upon interaction with polyamines without solvent, undergo acid cleavage, forming the corresponding amides. The copper(II) 1,3-ketoesterates are readily cleaved in CHCl₃ at 25°C in excess triethylenetetramine or ethylenediamine.Department of Fine Organic Synthesis, Institute of Organic Chemistry, Ural Branch, Russian Academy of Sciences, 620219 Ekaterinburg. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2591–2596, November, 1992.     

The interaction of biliar acids with 2-hydroxypropyl-β-cyclodextrin in solution and in the solid state

The interaction of two biliar acids (chenodeoxycholic acid and cholic acid) with 2-hydroxypropyl--cyclodextrin (HPCD) in solution and in the solid state was studied using different techniques. The formation of an inclusion complex with a 1:1 stoichiometry was suggested by the phase solubility studies. Both differential scanning calorimetry and X-ray diffractometry exhibited the amorphous state of the complex. The inclusion of both biliar acids into the HPCD cavity was confirmed by the¹³C-NMR studies. Cholic acid showed a weaker affinity with respect to chenodeoxycholic acid probably owing to the presence of a hydroxyl group onC(12) (12) close to the complexation site.     

2,2′-Diphenyl-Δ3,3′-bi-3H-indole-1,1′-dioxide: Competitive demethylation and redox reactions

Competitive demethylation and redox reactions induced by 2,2-diphenyl-^3,3-bi-3H-indole-1,1-dioxide,1 (dinitrone) on several nitrogen bearing compounds (pyridines, amides, indoles, hydrazones and amines) are reported.Es wird über kompetitive Demethylierungen und Redoxreaktionen an stickstoffhaltigen Verbindungen (Pyridine, Amide, Indole, Hydrazone und Amine) berichtet, die durch das Dinitron 2,2-Diphenyl-3,3-bi-3H-indol-1,1-dioxid induziert werden.

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2,2-Diphenyl-3,3t-bi-3H-indol-1,1t-dioxid: Kompetitive Demethylierung und Redoxreaktionen

     

Ab initio study of hydrazoic acid

SCF and CI calculations were carried out on the ground^1A state of HN₃. The equilibrium geometry and vibration frequencies were computed. The results point to a planar structure (groupC _s) but to a non-linear (170 °) N-N-N conformation. The calculated vibration frequencies are in fair agreement with experimental assignments.The dissociation path of the molecule to NH and N₂ products was investigated and compared to the isoelectronic reaction of diazomethane. The dissociation energy of hydrazoic acid is estimated to be about –8 kcal/mole, with a potential barrier to dissociation of about 30 kcal/mole.Boursier IRSIA     

Strukturelle Abwandlungen an N-Acetylneuraminsäure, 25. Mitt.: Synthese von Methyl-2-α-glycosiden von 4-epi-, 7-epi-, 8-epi- und 7,8-bis-epi-N-Acetylneuraminsäure

The -methylketoside of N-acetylneuraminic acid methylester (4) is transformed via the deacetylated compound5 into the 9,8-O-isopropylidenderivative6 which could be oxidized regioselectively by RuO₄ to the corresponding 4-oxo-sialic acid analogue7. Reduction with the boraneammonia complex produces a 1:1 mixture of6 and the desired -methylketoside of 9,8-O-isopropyliden-4-epi-N-acetyl-neuraminic acid methylester (8). Removing of the isopropylidene group gives the -methylketoside of 4-epi-N-acetylneuraminic acid methylester (9), which was further transformed to the ammonium salt of 4-epi-N-acetylneuraminic acid -methylketoside (10). On the other hand compound5 was turned into the 4,8,9-tri-O-t-butyldimethylsilylderivative11 a from which the corresponding 7-oxo-compound12 by oxidation with RuO₄ derives. The reduction of12 with BH₃ - NH₃ yielded a 1:1 mixture of the starting material11 a and the desired 7-epi-derivative13 a which gives either via the purified peracetylated -methylketosid of 7-epi-N-acetylneuraminic acid methylester (14) or a direct saponification the sodium salt of 7-epi-N-acetylneuraminic acid--methylketoside (15).Applying the Königs-Knorr procedure to the peracetylated 8-epi-N-acetylneuraminic acid methylester (16) gives rise to the formation of a 1:1 mixture of the corresponding - and -methylketosides17 and18 besides traces of the corresponding 2,3-dideoxy-2,3-dideohydro-sialic acid derivative19. After chromatographic separation of17 further saponification leads to the sodium salt of 8-epi-N-acetylneuraminic acid--methylketoside (20). In an analogous procedure the sodium salt of 7,8-di-epi-N-acetylneuraminic acid--methylketoside (25) was prepared starting from the peracetylated 7,8-di-epi-N-acetylneuraminic acid methylester (21), whereby a mixture of the - and -methylketosides22 and23 was formed in a ratio 95:5 besides traces of the peracetylated 2,3-dideoxy-2,3-didehydrosialic acid methylester (24).

On study leave from the Department of Chemistry, Postgraduate and Research Center, R.B.N.B. College, Shrirampur-413709 (MS), India     

X-ray and IR spectroscopic studies of specific intermolecular interactions inN′-substituted isonicotinohydrazides

_N-Thenylidene- andN-(o-nitrobenzylidene)hydrazides of isonicotinic acid have been studied by X-ray structural analysis and IR spectroscopy. In the crystalline state, these molecules are linked through intermolecular N—H ... Np_y hydrogen bonds. Carbonyl groups are not involved in intermolecular hydrogen bonds. However, it was found that the C=O group participates in an attractive interaction with the sulfur atom of the thiophene group. The energy of this interaction is comparable with the energies of intermolecular C=O ... H—N hydrogen bonds in amides.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 896–900, April, 1996.     

Reaction Between 5-Isopropylidene-2,2-dimethyl-1,3-dioxane-4,6-dione and <Emphasis Type="Italic">tert</Emphasis>-Butyl Isocyanide in the Presence of Primary or Secondary Amines

Summary. 5-Isopropylidene-2,2-dimethyl-1,3-dioxane-4,6-dione (the condensation product of Meldrums acid and acetone) reacts smoothly with tert-butyl isocyanide in the presence of primary or secondary amines to produce N-tert-butyl-2,2-dimethylbutyramide derivatives and/or 1-tert-butyl-4,4-dimethyl-2,5-dioxopyrrolidine-3-carboxamides in good yields.     

Ab initio SCF investigation of the intramolecular hydrogen bonding in δ-aminopentanoic acid

The potential energy surface of the neutral form of-aminopentanoic acid was investigated by means of ab initio 4-31G SCF calculations. Four symmetry unique local minima are stabilized by an intramolecular O-H NH₂ hydrogen bond. The geometries, energies, and wave numbers of these conformers are reported. The hydrogen bond is discussed with respect to all reactions of these conformers and in comparison with the homologues glycine,-alanine, and-aminobutyric acid and also with the bimolecular adducts between formic acid, acetic acid, and propionic acid, on the one hand, and ammonia, methylamine, and ethylamine, on the other hand.     

Aromatische Spirane, 16. Mitt.: Darstellung von monound dianellierten 2,2′-Spirobiindan-1,1′-dionen

Summary The spiroketones19, 21, 24, 27, and31 were prepared by cyclisation of the dicarboxylic acids and their acid chlorides, resp., (18, 20, 22, 23, 25, 26, 28, and30) with polyphosphoric acid (PPA) or SnCl₄. The latter compounds were synthesized by alkylation of the appropriate -keto esters10, 11, 12, and13 with the benzyl chlorides14, 15, 16, and subsequent retro-Claisen-reaction. The spiro compounds21a and39 were obtained byPPA-cyclisation of the keto acids35 and38, which in turn were prepared by aldol-reaction of the ketoness-hydrindacen-1-on and9a with phthalaldehydic acid to the olefinic keto acids33 and36 followed by catalytic hydrogenation.

     

Isocamphanyl-γ-butyrolacton,ein neuer Sandelholzriechstoff

The synthesis of a new compound with a sanddalwood odour is described. The synthesis of the lactone1 has been designed by molecular considerations: a bicyclus with a side chain containing 5–7 carbon atoms and an oxygene containing osmophoric group. One route to synthesize1 leads from the ketone3 via theMannich base4 to the -ketonitrile6 which after hydrolysis to the -keto acid7 and reduction of the latter cyclises spontaneously to1. A shorter route starts from the -bromoketone13 which could be transformed by malonic ester synthesis into7. Other synthetic routes, e.g. cyanoethylation to the homologous -lactone16 aldol condensation, alkylation, carboxymethylation and carboxyethylation of3 failed as well as the preparation of the oxazoline protected 3-bromopropionic acid for aGrignard synthesis with3. 1 exhibits a sweet, warm odour, of sandalwood with an interesting note of cedarwood.

Teil der Diplomarbeit vonSchindler, K., Universität Wien, 1979.