Cyclization of cembrane diterpenoids. V. Selectivity of the formation of a product of the cyclization of cembrene under the action of N-bromosuccinimide,and the crystal structure of this product

Under the action of N-bromosuccinimide in aqueous acetone, cembrene has given a low yield of a cyclization product, the structure and stereochemistry of the molecule of which have been established by x-ray structural analysis. In contrast to the cyclization of cembrene under the action of formic acid, in the reaction under consideration a 1,5-hydride shift in the last stage dominates substantially over the splitting out of a proton from the methyl group at C-4. Novosibirsk Institute of Organic Chemistry, Siberian Division of the Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 687–691, September–October, 1993.     

Oxidative transformations of cembrane diterpenoids IV. Photooxidation of cembrene

The photooxidation of cembrene by singlet oxygen is a stereoselective reaction and it is stereochemically similar to the epoxidation of cembrene by peracids. From the mixture of the photooxidation products of cembrene after its treatment with sodium tetrahydroborate four allyl alcohols have been isolated and the structures of two of them, previously undescribed, have been established on the basis of their spectral characteristics. The main component of these alcohols is cembra-2E, 4Z, 7E, 10E-tetraen-12S-ol.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 60–67, January–February, 1981.     

Oxidative transformations of cembrane diterpenoids III. Epoxycembrenes

Summary 1. It has been established that the epoxidation of cembrene with perbenzoic and peracetic acids takes place stereospecifically at each of the trisubstituted double bonds with the formation of 4S,5R-, 7S,8S-, and 11S,12S-monoepoxycembrenes, the structures and absolute configurations of which have been established by spectral methods.2. Epoxidation of cembrene at the C₁₁–C₁₂ double bonds under the conditions used takes place preferentially as compared with epoxidation at the C₇–C₈ double bond.Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. Novosibirsk State University. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 525–531, July–August, 1977.     

Nitroazines. 3. Nitroacetonitrile in the synthesis of nitroazines

Azolo-annelated nitro-1,2,4-triazines have been obtained by the cyclization, thermally or under the action of acids, of the products of the coupling of diazopyrazoles or diazo-1,2,4-triazoles with nitroacetonitrile.For communication 2, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 682–688, May, 1985.     

Cyclization of cembrane diterpenoids. VI. Products of the cyclization of 5β-acetoxyisocembrol

The structures and the stereochemistries of all the main products of the carbocyclization of 5β-acetoxyisocembrol on its interaction with aqueous formic acid in chloroform have been established. This reaction takes place more selectively than the cyclization of cembrene under the same conditions and is distinguished by the complete predominance in its last stage of the 1,5-hydride shift from C-15 to C-4 over the splitting out of a proton from the C(4)-methyl group.     

Oxidative transformations of cembrane diterpenoids I. Oxidation of cembrene with chromium trioxide

Summary 1. The oxidation of cembrene with chromium trioxide in aqueous sulfuric acid (the Jones reagent) and in aqueous acetone has given norcembra-2,7,11-trien-4-one, norsolanadione, (3E, 8E)-5-isopropyl-8-methyltrideca-3,8-diene-2,12-dione, and five new compounds the structures of which have been established on the basis of their spectra.2. Oxidation with chromium trioxide in aqueous acetone, in contrast to oxidation with the Jones reagent, takes place stereospecifically—the C₁₁-C₁₂ double bond of cembrene is not affected.Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 313–320, May–June, 1976.     

Stereoselectivity of the exhaustive epoxidation of cembrene by peracetic acid. Crystalline and molecular structure of triepoxycembrene

The epoxidation of the diterpene hydrocarbon cembrene with peracetic acid in methylene chloride in the presence of sodium bicarbonate forms a single triepoxide — 4,5:7,8:11,12-triepoxycembrene with the 4S, 5R, 7S, 8S, 11S, 12S configuration of the asymmetric centers. The structure and stereochemistry of triepoxycembrene have been determined with the aid of x-ray structural analysis.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 174–178, March–April, 1981.     

Oxidative transformations of cembrane diterpenoids. II. Cembra-2,7,11-triene-4,5-diols

Summary 1. The oxidation of cembrene with chromium trioxide in aqueous acetone forms, together with other compounds, the products of its hydroxylation at the C₄ double bond — cembra-2,-7,11-triene-4,5-diols epimeric at the C₄ double bond.2. On the basis of chemical and spectral characteristics, it has been established that these diols have the 4S, 5R and 4R, 5R configurations, respectively.Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR, and Novosibirsk State University. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 54–59, January–February, 1977.     

Pheromones of insects and their analogs LIII. Synthesis of ferrulactone I —a pheromone ofCryptolestes ferrugineus

8-Acetoxy-3, 7-dimethyl-l-(phenylsulfonylacetoxy)octa-2E, 6E-diene has been synthesized, and its cyclization under the action of zerovalent palladium followed by desulfurization with the aid of sodium amalgam has led to ferrulactone I — one of the macrolide components of the aggregation pheromone of the rust-red grain beetle (Cryptolestes ferrugineus).Institute of Organic Chemistry, Urals Scientific Center of the Russian Academy of Sciences, 450054, Ufa pr. Oktyabrya, 71. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 932–935, November–December, 1996. Original article submitted May 27, 1996.     

NMR spectra and conformation of cembrene in solution

Using dimeric NMR spectroscopy, a complete interpretation of the¹H and¹³C NMR spectra of the diterpene hydrocarbon cembrene has been made. The experimental values of the SSCs for the¹H atoms in the PMR spectra of cembrene agree well with those calculated for the lowest-energy (crystal) conformation. In the light of the observation of intramolecular NOEs and of the low-temperature¹³C NMR spectra, it has been concluded that the cembrene molecule retains the crystal conformation in solution.Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 455–459, July–August, 1991.     

Electrochemical cyclization of tetramethyl esters of 2-substituted propane-1,1,3,3-tetracarboxylic acids in the presence of salts of hydrohalic acids

The chemical and electrochemical cyclization of tetramethyl esters of 2-substituted propane-1,1,3,3-tetracarboxylic acids in the presence of hydrohalic acid salt mediators were studied. It was found that the chemical variant of the cyclization of the corresponding ,'-dianions of esters of propane-1,1,3,3-tetracarboxylic acids by the action of iodine or bromine is substantially inferior to the electrochemical variant. In the latter case, the esters of substituted cyclopopane-1,1,2,2-tetracarboxylic acids are formed in a 87–98% yield. The tetramethyl ester of 2-isopropylpropane-1,1,3,3-tetracarboxylic acid, which under the electrolysis conditions decomposes according to a Michael retroreaction is an exception.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2783–2789, December, 1990.     

Composition of the neutral fraction from the oleoresin ofPinus sibirica

Conclusions 1. From the neutral fraction of the oleoresin ofPinus sibirica R. Mayr have been isolated new macrocyclic diterpene compounds-isocembrene (I) and isocembrol (VI).2. It has been shown that isocembrol is readily dehydrated into cembrene and isocembrene.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 1, pp. 10–14, 1969     

Research in the chemistry of heterocyclic quinoneimines. 3. Oxidative cyclization of 2,5-diarylamino-substituted 1,4-benzoquinone-4-phenylimines — Simple method for the preparation of 2-arylamino-5-aryl-3-phenazinones

2,5-Diarylamino-1,4-benzoquinone-4-phenylimines, which are formed in the reaction of 1,4-benzoquinone-4-phenylimine with aromatic amines, are converted under oxidative conditions to products of intramolecular oxidative cyclization, viz., 2-arylamino-5-aryl-3-phenazinones.See [4] for Communication 2.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 330–333, March, 1984.     

Mass-spectrometric study of the cyclization of diazo ketones. 1. Cyclization of 1-diazo-3-sulfonylaminopropan-2-ones to N-sulfonylazetidin-3-ones

A comparison of the mass spectra of 1-diazo-3-sulfonylaminopropan-2-ones and N-sulfonylazetidin-3-ones makes it possible to conclude that under the conditions of electron impact and chemical ionization the molecular ions of diazo ketones lose a molecule of nitrogen and undergo partial cyclization to the corresponding azetidinones without undergoing the Wolff rearrangement.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 334–342, March, 1982.     

Synthesis and properties of azoles and their derivatives. 33. Synthesis of 1,3,4-oxadiazoles that contain an indolyl group

2,5-Disubstituted oxadiazoles with indole residues were synthesized by condensation of the hydrochlorides of the corresponding imido esters with hydrazines, as well as by cyclization of hydrazides by the action of POCl₃. 2-Substituted oxadiazoles of the same series were obtained by condensation of the corresponding hydrazides with ethyl orthoformate.See [1] for Communication 32.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 343–347, March, 1982.     

Synthesis of derivatives of a new heterocyclic system — 1,2,3,4-tetrahydrobenzofuro[3,2-c]pyridine

Derivatives (Iva–f) of the heretofore unknown 1,2,3,4-tetrahydrobenzofuro[3,2-c]pyridine heterocyclic system were synthesized by the cyclization of aryl ethers of the oximes of piperidones (IIIa–f) under acid conditions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1469–1472, November, 1971.     

Synthesis of 3-acetyl-2-amino-4-pyridone

A method hxsynthesizing 3-acetyl-2-amino-4-pyyridone has been suggested. The synthesis involves the condensation of dimethylformamide dimethylacetal at the NH₂ group of diphenylboron chelate diacetylketene aminal followed by its intramolecular cyclization under the action of NaOMe in MeOH.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 177–179. January, 1996.     

Catalytic claisen amino rearrangement of N-(cyclo)alkenylarylamines and intramolecular cyclization of ortho-alkenylarylamines

Aromatic Claisenamino rearrangements of N-alkenyl-2-methylindoline under the action of Lewis acids leads to 7-alkenyl-2-methylindolines in high yield. Cyclization of ortho-alkenyl compounds was effected in polyphosphoric acid (PPA) and by UV irradiation. Heating 7-(1-methyl-2-butenyl)-2-methylindoline in PPA is accompanied by 1,3-methyl shift in the alkenyl substituent with subsequent cyclization at the aromatic nucleus.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1342–1346, October, 1992.