Reaction of 3,4-dioxohexane-1,6-dioic acid esters with 2,4-dinitrophenylhydrazine

Reaction was studied of 3,4-dihydroxyhexa-2,4-diene-1,6-dioic acid esters with 2,4-dinitrophenylhydrazine that led to the formation of esters of (3E)-3-[2-(2,4-dinitrophenyl)-hydrazinylidene]-4-oxohexane-1,6-dioic and (3E,4E)-3,4-bis[2-(2,4-dinitrophenyl)hydrazinylidene]-hexane-1,6-dioic acids. The structural features of compounds synthesized were established from the data of IR and NMR spectra and X-ray diffraction (XRD) analysis.     

1,3,4,6-Tetracarbonyl Compounds: VI. Synthesis of 2-Substituted 6-Aryl-3,4-dihydroxy-6-oxo-2,4-hexadienoic Acid Esters and Amides

The Knoevenagel reaction of 5-aryl-2,3-dihydrofuran-2,3-diones with ethyl cyanoacetate or malonodinitrile yields 2-substituted 6-aryl-3,4-dihydroxy-6-oxo-2,4-hexadienoic acid esters or amides which exhibit biological activity. The structure of the products is discussed, taking into account the structure of known 3,4-dihydroxy-6-oxo-2,4-hexadienoic acid esters and 1,6-diaryl-3,4-dihydroxy-2,4-hexadiene-1,6-diones.     

Triterpenoids from Abies species X. Two new 3,4-secotriterpene acids from the oleoresin of the silver fir

Two new 3,4-secotriterpene acids have been isolated in the form of dimethyl esters from the acid fraction of the oleoresin of the silver firAbies alba Mill. On the basis of spectral characteristics and the results of a chemical correlation with the known triterpenoids methyl abiesolidate, dimethyl abiesonate and methyl firmanoate it has been established that they are (25R)-3,4-seco-9β-lanosta-4(28),7-dien-23-one-3,26-dioic acid and (25R)-3,4-seco-abiesa-4(28),7,14(30)-trien-23-one-3,26-dioic acid. Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 765–770, November–December, 1990.     

Triterpenoids from Abies species X. Two new 3,4-secotriterpene acids from the oleoresin of the silver fir

Two new 3,4-secotriterpene acids have been isolated in the form of dimethyl esters from the acid fraction of the oleoresin of the silver firAbies alba Mill. On the basis of spectral characteristics and the results of a chemical correlation with the known triterpenoids methyl abiesolidate, dimethyl abiesonate and methyl firmanoate it has been established that they are (25R)-3,4-seco-9-lanosta-4(28),7-dien-23-one-3,26-dioic acid and (25R)-3,4-seco-abiesa-4(28),7,14(30)-trien-23-one-3,26-dioic acid.Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 765–770, November–December, 1990.     

Stereoselective hydrocoupling of cinnamic acid esters by electroreduction: application to asymmetric synthesis of hydrodimers

The electroreduction of Ar-substituted methyl cinnamates in acetonitrile gave all-trans cyclized hydrodimers stereoselectively (58 approximately 90% de). In all cases, small amounts (<10% yield) of meso hydrodimers were also formed. The electrolysis was performed conveniently using an undivided cell at a constant current. The transition states for the hydrocoupling were calculated with semiempirical methods. The all-trans cyclized hydrodimers were transformed to C(2)-symmetric dl-3,4-diaryladipic acids and trans-3,4-diarylcyclopentanones. The chiral auxiliary [(1R)-exo]-3-exo-(diphenylmethyl)borneol, prepared from (1R)-(+)-camphor, was highly effective for the stereoselective hydrocoupling of its cinnamates by electroreduction. From the resulting hydrodimers, (3R,4R)-3,4-diaryladipic acid esters and (3R,4R)-3,4-diarylhexane-1,6-diols were synthesized in 87-95% ee.     

Synthesis of gross-conjugated polyenic dialdehydes and carboxylic acid esters

Conclusions Methylenemalonaldehyde was used in a convenient method for the synthesis of 4-aryl-and 4-heteroarylmethylenehepta-2,5-diene-1,7-dials and dimethyl esters of 6-aryl- and 6-heteroarylmethyleneundeca-2,4,7,9-tetraene-1,11-dioic acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2614–2616, November, 1987.     

New humulane-type sesquiterpenes from the liverworts Tylimanthus tenellus and Marchantia emarginata subsp. tosana

The ether extract of the New Zealand liverwort Tylimanthus tenellus produced three new sesquiterpenes, together with (+)-3,11-eudesmadiene and (-)-4(15),11-eudesmadiene which were enantiomeric to those isolated from higher plants. The structures of the new sesquiterpenes were established by 2D NMR spectral data and/or X-ray crystallographic analysis. Those structures were shown to be humulane type sesquiterpene alcohol, and its esters of 2,4-hexadienedioic acid 3,4-dihydroxy-2,5-diphenyl-gamma-lactone. 1,6-Humuladien-10-ol was also isolated from Japanese liverwort Marchantia emarginata subsp. tosana. The absolute configuration of 1,6-humuladien-10-ol was determined by (1)H-NMR resolution of its diastereomeric methoxy-alpha-trifluoromethylphenylacetyl (MTPA) esters. It was shown to be (3S,10R)-1,6-humuladien-10-ol.     

Stereoselective hydrocoupling of [(1R)-exo]-3-exo-(diphenylmethyl)bornyl cinnamates by electroreduction

[reaction: see text]. The chiral auxiliary [(1R)-exo]-3-exo-(diphenylmethyl)borneol, synthesized from (1R)-(+)-camphor in three steps, was highly effective for the stereoselective hydrocoupling of its cinnamates by electroreduction. From the resulting hydrodimers, (3R,4R)-3,4-diaryladipic acid esters and (3R,4R)-3,4-diarylhexane-1,6-diols were synthesized in 87-95% ee.     

Two new echinocystic acid derivatives catalyzed by filamentous fungus Gliocladium roseum CGMCC 3.3657

Biotransformation of Echinocystic acid (EA,1) using G. roseum CGMCC 3.3657 has been investigated, which leads to the isolation and identification of two novel Echinocystic acid derivatives, 4, 16α-dihydroxy-3,4-seco-olean-12-en-3,28-dioic acid (2) and 16α-hydroxy, A-homo-3α-oxa-olean-12-en-3-one-28-oic acid (3). Their structures have been elucidated by analysis of spectroscopic data. This biocatalysis could serve as an efficient tool complementary to classical chemical methods for the transformation of EA.     

Synthesis of 1,3,4,6-tetraoxo compounds

The two-step method of synthesis of 1,3,4,6-tetraoxocompounds with different terminal substituents is developed. By condensation of alkyl methyl ketones with dimethyl oxalate new 1,6-dialkyl-substituted 1,3,4,6-tetraoxohexanes are obtained. The esters of 3,4,6-trioxoalkanoic acids are synthesized by the condensation reaction of alkyl acetates with dialkyl oxalates and alkyl methyl ketones. By the reaction of ethyl acetate with diethyl oxalate and methyl acetate the mixed diester of 3,4-dioxo-1,6-hexanedioic (ketipic) acid has been first prepared. Specific structural features of the synthesized compounds are discussed basing on the data of the IR, NMR, and XRD diffraction (XRD) analysis.     

Unusual Reaction of Sodium 1,6-Dioxo-2,4-alkadiene-3,4-diolates under Acid Hydrolysis Conditions

The reaction of sodium 1,6-dioxo-2,4-alkadiene-3,4-diolates with HCl solution afforded unexpected hydrolysis products, namely (2Z)-2-hydroxy-4-oxobut-2-enoic (2,4-dioxobutanoic) acid esters. The structural features of the synthesized compounds were discussed on the basis of IR, ¹H NMR spectroscopy, mass spectrometry and X-ray diffraction analysis data.     

Synthesis of pyrylium salts and heterocyclic nitrogen bases from cycloalkenylacetic acid esters

2-Alkyl-6-methoxy-3,4-tetramethylene- and 3,4-pentamethylenepyrylium perchlorates were obtained by acylation of cycloalkenylacetic acid esters with aliphatic acid anhydrides. 2-Methyl-6-methoxy[2,3-c]cholestanopyrylium perchlorate was similarly synthesized. 2-Alkyl-3,4-tetramethylene-6-pyridones were isolated by treatment of 2-alkyl-6-methoxy-3,4-tetramethylene-pyrylium perchlorates with excess concentrated ammonium hydroxide. 2-Methyl-3,4-pentamethylene-6-aminopyridine was obtained by the action of excess concentrated ammonium hydroxide on 2-methyl-6-methoxy-3,4-pentamethylenepyrylium perchlorate.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1323–1326, October, 1976.     

Structures of new secofriedelane and friedelane acids from Calophyllum inophyllum of French Polynesia

Three new friedelane-type triterpenoids, 3,4-secofriedelan-3,28-dioic acid (1), 27-hydroxyacetate canophyllic acid (2) and 3-oxo-27-hydroxyacetate friedelan-28-oic acid (3), were isolated from the leaves of Calophyllum inophyllum (Clusiaceae) grown in French Polynesia. Their structures were established by the concerted application of 2D NMR techniques including gs-COSY, gs-HMQC and gs-HMBC.     

Tetracarbonyl Systems: VII. Reactions of 1,3,4,6-Tetracarbonyl Compounds with o-Aminothiophenol in the Synthesis of Regioisomeric 3(2)-Aroylmethylene-1,4-benzothiazin-2(3)ones

In reaction of 1,6-diaryl-3,4-dihydroxy-2,4-hexadiene-1,6-diones with o-aminothiophenol (3Z)-3-aroylmethylene-3,4-dihydro-2H-1,4-benzothiazin-2-ones were obtained in a preparative yield. In solution of the latter compounds an enamine-imine tautomerism was observed. In reaction of ethyl esters or amides of 2-substituted 6-aryl-3,4-dihydroxy-6-oxo-2,4-hexadienoic acids with the o-aminothiophenol regioisomeric 2-aroylmethylene-2H-1,4-benzothiazin-3(4H)-ones were formed.     

Nanoparticles of lipoic acid esters: preparation and antioxidant effect

Five lipoic acid esters were synthesized, and their nanoforms based on copolymer Pluronic F68 and phosphatidylcholine were obtained. The most pronounced antioxidant effect on neutrophils activated by phorbol-12-myristate-13-acetate was shown by the nanodispersion containing the derivative of lipoic acid with hexane-1,6-diol, reducing the concentration of reactive oxygen species by 7.5 times.     

Triterpenoids from species ofAbies hill. II. Abiesolidic acid — A new 3,4-secolanostanoid from the oleoresin ofAbies sibirica

The oleoresin of the Siberian fir has yielded a new 3,4-secolanostanoid for which the structure of (20R,23S,25R)-3,4-seco-9β-lanosta-4(28),7-dien-26,23-olid-3-oic acid has been established by x-ray structural analysis. The pathways of the mass-spectrometric fragmentation of this acid and its esters have been investigated.     

Synthesis,Structure, and Biological Activity of Products of Reactions of 3,4-Dioxohexane-1,6-dioic Acid Esters with 2-Aminophenol

Bioactive derivatives of 1,4-benzoxazine have been prepared via reactions of 3,4-dioxohexane-1,6- dioic (ketipic) acid esters with 2-aminophenol. (2'Z)-2,2'-(2-Hydroxy-2H-1,4-benzoxazin-2-yl-3-ilidene)diacetic acid esters or (2Z)-[2-oxo-2H-1,4-benzoxazin-3(4H)-ylidene]acetic acid esters can be formed depending on the conditions. The structures of the products of dialkyl ketipate esters reactions with 2-aminophenol were determined by means of X-ray diffraction. It has been demonstrated that the prepared compounds exhibit antimycotic activity against test cultures of plant pathogenic fungi (Fusauium sp., Alternarium sp., and Bipolaris soraciniana).     

Reactions of ethyl oxamate and dialkyl oxalates with anthranilic acid derivatives

Ethyl oxamate reacted with anthranilic acid derivatives at the amide or the ester group leading to the formation of respective esters or amides. A simple method was developed for preparation of alkyl 3-amino-4-oxo-3,4-dihydroquinazoline-2-carboxylates.     

endo-1,4,5,6,7,7-hexachlorobicyclo[2.2.1]hept-5-ene-2-carboxylic acid, a superior resolving agent for the high-performance liquid chromatographic separation of enantiomers of hydroxylated derivatives of two azaaromatic hydrocarbons

The high-performance liquid chromatographic (HPLC) separation of enantiomers of oxide and hydroxy derivatives of dibenz[a,j]acridine and 7-methylbenz[c]acridine was investigated on a chiral stationary phase chromatography column using commercially available columns. In most cases either poor or no separation of enantiomers was achieved. Normal-phase separation of diastereoisomeric ester derivatives of the hydroxy compounds, prepared from commercially available (-)-menthoxyacetic acid or (+)-alpha-methoxy-alpha-(trifluoromethyl)phenylacetic acid, was investigated. No separation of the diastereoisomeric esters of trans-3,4-dihydroxy-3,4-dihydrodibenz[a,j]acridine was observed. However, diastereoisomeric esters prepared from (+)-endo-1,4,5,6,7,7-hexachlorobicyclo[2.2.1]hept-5-ene-2-carboxyl ic acid [(+)-HCA] were easily separated. Using the three chiral acids, diastereoisomers were prepared from sixteen hydroxy derivatives of dibenz[a,j]acridine and 7-methylbenz[c]acridine. (+)-HCA esters gave good to excellent HPLC separations which were superior to those achieved using other chiral acids in most cases. The enantiomeric composition of trans-3,4-dihydroxy-3,4-dihydrodibenz[a,j]acridine formed as a major rodent liver microsomal metabolite of dibenz[a,j]acridine was determined using (+)-HCA.     

Reactions of N-phenylamide and phenyl (thio)esters of 3-phenylpropiolic acid with benzene under superelectrophilic activation

N-Phenylamide and phenyl (thio)esters of 3-phenylpropiolic acid add benzene in the presence of CF₃SO₃H or AlX₃ (X = Cl, Br) to give 4,4-diphenyl-3,4-dihydroquinolin-2-one, 4,4-diphenyl-3,4-dihydrocoumarin, and 4,4-diphenyl-3,4-dihydrothiocoumarin, respectively.