Search

Reaction of (+)-3-carene trans-epoxide with sodium thiolates in methanolic solution in a microwave oven at 140 °C for 35–40 min affords corresponding (1S,3S,4S,6R)-4-sulfanylcaran-3-ols in 75–95% yields.

The preparation of (–)-caronaldehyde from monoterpene hydrocarbon ( + )-3-carene is described.

Terpenic α-amino ketones have been prepared in good yield by treatment of the corresponding α-amino oximes with Ti(III) salts; all other known methods of deoximation give unacceptably low yields.

Syntheses of new 1,2-azole-type fused heterocycles based on the α-pinene molecule are described.

When treated with sodium borohydride in boiling acetonitrile, α-amino oximes are transformed to the corresponding ω-amino nitriles in 31–87% yield. Easily available α-amino oximes with cyclohexane, methylcyclohaxene, p-menthane, carane, pinane, and caryophyllane carbon skeletons are tested. The reaction was found to proceed only in an aliphatic nitrile medium; the specific role of a nitrile is discussed. Beckmann synchronous mechanism was confirmed for the fragmentation stage followed by reduction of the intermediate immonium salt.

Treatment of dimeric nitrosochlorides derived from unsaturated hydrocarbons 1-methylcyclohexene, (+)-3-carene and limonene with 1,2-phenylenediamine results in the formation of hexahydrophenazine derivatives in good yields (48–66%). Treatment of cyclohexene nitrosochloride under the same reaction conditions leads to tetrahydrophenazine. Stereochemistry of the phenazine derivatives and possible reaction pathway are discussed.

Treatment of bicyclic monoterpene diketone with a modified carane skeleton with acylhydrazines results in stable N-acylpyrazolinols in 26-86% yield.

Reaction of α,β-unsaturated monoterpenic ketones-carvone, pinocarvone and 2-caren-4-one - with the sodium salt of diethylphosphite in diethylphosphite media results in regioselective addition to the conjugated carbon-carbon double bond and formation of the corresponding oxophosphonates.

Novel 2,5-dimethylenethiazolidin-4-one derivatives have been prepared by reaction of malonthioamide derivatives with dimethyl acetylenedicarboxylate. These compounds exist as separate (E,Z)- and (Z,Z)-isomers or as a mixture. The (E,Z)-isomer is formed as the initial product which transforms to the (Z,Z)-isomer under mild conditions. The structures of the obtained compounds have been confirmed by IR and NMR spectroscopy.

The first example of the ring transformation of 1,2,3-thiadiazoles involving four atoms of the side chain to form 5H-[1,2,3]triazolo-[5,1-b][1,3,4]thiadiazines is presented.

Amidines react in the presence of NaHCO3 with β-chlorovinyl ketones, prepared regioselectively by the reaction of 2-acetylcyclo- pentanone-type diketones with PPh3-CCl4 in 73–78% yield, to afford 2-alkyl (aryl)-pyrimidines annelated with cyclopentane derivatives in 79–87% yields.

The reaction of N-(ethoxycarbonyl)methyl substituted ethyl 6,7-difluoro-, 6,7,8-trifluoro- and 5,6,7,8-tetrafluoro-4-oxo-1,4-dihydro-quinoline-3-carboxylates with methyl methacrylate results in the [3 + 2] adducts, hexahydropyrrolo[1,2-a]quinolones, which can be precursors of [a]-fused fluoroquinolones.

The reaction of dibenzylphosphine oxide with myrtenoic acid nitrile in tert-butyl methyl ether in the presence of sodium hydride results in the formation of substituted aminophospholene oxide in good yield (83%).

Oxidation of triterpenoids methyl ursonate, acetylbetulone, and allobetulone with atmospheric oxygen in the presence of ButOK in ButOH afforded the corresponding 2,3-diketo derivatives in 90-97% yields. These derivatives exist predominantly as tautomers containing the enolized keto group at the C(2) atom. Their reactions with o-phenylenediamine gave rise to the corresponding quinoxalines in 85-95% yields.

Treatment of triterpenoids derived from ursolic and glycyrrhetinic acids with the oxidative mixture H 2 O 2 -(CF 3 COO) 2 Hg-Na 2 CO 3 -THF results in oxidative decarboxylation. The reaction of 3 O -acetylursolic acid ( 1 ) and 3 O -acetyl-18β-glycyrrhetinic acid ( 3 ) affords stable norhydroperoxides, whereas decarboxylation of 3 O -acetyl-11-oxoursolic acid ( 6 ) leads to unstable norhydroperoxide. The difference in properties of the norhydroperoxides is explained by the presence of a conjugated ketone, which activates the 12,13-C=C double bond for nucleophilic addition and makes possible intramolecular Michael-type addition of peroxo anion.

Using a number of cyclic α,β-unsaturated oximes of the terpene series and some simplest model compounds as examples, unsaturated oximes bearing a hydrogen atom at the β-carbon atom were demonstrated to be converted into β-hydroxyiminonitroalkenes under the action of sodium nitrite and acetic acid in methanol. In the case of the introduction of an alkyl substituent at the terminal carbon atom of the diene C=C—C=NOH fragment, the reaction performed under the same conditions gave rise exclusively to conjugated ketone (a deoximation product).

The reaction of nitroso chlorides of natural monoterpene hydrocarbons, 3-carene and α-pinene, with simple α,ω-diamines (1,2-diaminoethane, 1,3-diaminopropane, piperazine, 1,6-diaminohexane, diethylenetriamine) results in the formation of α-amino oximes and bis-α-amino oximes. The product structures were proved by spectroscopy. The procedures of separation and purification of diamino oximes and diamino dioximes are described. Detailed analysis of the 1H and 13C NMR spectra of the new chiral nitrogen-containing derivatives was carried out.

2-(Alkoxycarbonylmethylidene)-4-aryl-5-(dialkylamino)thiophen-3(2H)-ones were synthesized by condensation of N,N-(dialkyl)arylthioacetamides with dialkyl acetylenedicarboxylates. Intermediate substituted vinylic sulfides were isolated. When heated or in the presence of an acid or a base, they undergo cyclization into thiophenes.

Reaction of 3-nitro- and 3-ethoxycarbonyl-1,2,4-triazolo[5,1-c]-1,2,4-triazin-4-ones with 1-adamantanol (or 1-adamantyl nitrate) in concentrated sulfuric acid or with 1-bromoadamantane in sulfolane affords N-adamantyl derivatives. The adamantylation of 3-nitro-1,4-dihydro-7H-1,2,4-triazolo[5,1-c]-1,2,4-triazin-4-one yields a mixture of N8- and N1-isomers that undergo interconversion in concentrated sulfuric acid along intermolecular mechanism.

Chemically induced dynamic nuclear polarization (CIDNP) and electron paramagnetic resonance (EPR) techniques have been used to study the paramagnetic species formed during the photolysis of the alkaloid lappaconitine and its synthetic analogues in solution. Lappaconitine is a photosensitive antiarrhythmic and hypertension drug, whose major photoproduct (N-acetyl anthranilic acid) is also a potent photosensitizer. Both these compounds are lipophilic and might bind efficiently to cell membranes thereby causing phototoxic damage. Photolysis of natural lappaconitine (I) as well as its N(20) des-ethyl derivatives (N-Bz (II), N-Me (III), N-H (IV), and N(O)-Et (V)) results in cleavage of the ester bond with the formation of N-acetyl anthranilic acid (VIII) and corresponding enamine. The lappaconitine derivative V shows maximum photostability which correlates with reference data about its low toxicity. It was shown that the primary reaction step is electron transfer from the amino group to the anthranilic fragment of lappaconitine resulting in an intermediate biradical. The final products are formed via fragmentation of the neutral lappaconitine radicals.

Certain cis-3-substituted 2,2-dimethyl-1-(2-oxopropyl)-cyclopropanes are effectively reduced by baker's yeast to give predominantly (S) -isomers of the corresponding 2-hydroxypropyl derivatives. Reduction of the 2-oxopropyl group proceeds more rapidly (ca. 3.5 times) and with higher stereoselectivity [(S):(R) = 98:2] when the group is attached to the (S)-carbon of the cyclopropane unit than of the keto group attached to the (R)-carbon [(S):(R) = (88):(12)]. Yeast reduction of the keto derivatives is effectively carried out when substituents at C-3 are as follows: CH2COOCH3, -CH2COCH3, -CN, -CH2CN, -CH2CH2OH, and the relative rates of reduction are 36:36:15:13:7. No reduction occurs when substituents at C-3 are propyl, 2-methyl-2-hydroxypropyl or 2-methyl-1,3-dioxolan-2-yl methyl groups.

An oxo nitrile prepared from (+)-3-carene was converted to (1 R)-cis-chrysanthemylamine by two synthetic methods involving several steps

The FeCl 3 -catalyzed reaction of α,β-unsaturated oximes with ethyl acetoacetate resulted in Michael addition followed by ring closure to produce substituted nicotinic acid derivatives in a very efficient way.

Reactions of linalyl acetate, dehydrolinalool and geranyl acetate with NOCl result in selective addition to the Δ6,7 double bond.

New heterocyclic compounds, pyrimidines annelated with modified terpenic frames, were synthesised from positional isomers of β-enaminones derived from limonene and (+)-3-carene.

The reaction of NOCl with cembrene at –50 °C in CH2Cl2 results in 1,2-addition to the conjugated system of double bonds.

Under the conditions of the Mannich reaction, 3-substituted oximes of caran-4-one undergo aminomethylation at the α-carbon atom to oxime. The reaction takes place successfully only in a mixture of methanol and acetic acid to produce α-aminomethyl derivatives in 25–83% yields. The secondary or tertiary amino group at the α’-position is eliminated under the reaction conditions to form derivatives of α,β-unsaturated oxime, while sulfur-containing substituents remain unchanged.

A three component condensation of 6-quinolylamine with 4-bromo-or 4-methoxybenzaldehyde, and 1,3-cyclohexanedione or dimedone gave 12-(4-bromophenyl)-and 12-(4-methoxyphenyl)-9,9-dimethyl-8,9,10,12-tetrahydro-7H-benzo[b][4,7]phenanthrolin-11-ones. The reaction intermediates obtained were N-arylmethylene-6-quinolylamines, 2-arylmethylenebis(1,3-cyclohexanediones), 3-(6-quinolylamino)-2-cyclohexenone, and 5,5-dimethyl-3-(6-quinolylamino)-2-cyclohexenone.

A verbanone reaction with acetonitrile under Ritter reaction conditions led to a selective formation of o-menthane derivatives, a mixture of stereoisomeric cis-and trans-8-acetamido-o-menthones. The streoisomers ratio depends on the reaction conditions and the character of acid catalyst used.

Reaction of α,β-unsaturated monoterpenic ketones-carvone, pinocarvone and 2-caren-4-one - with the sodium salt of diethylphosphite in diethylphosphite media results in regioselective addition to the conjugated carbon-carbon double bond and formation of the corresponding oxophosphonates.

A new method was developed for the one-step synthesis of spiro derivatives of fused quinolines by the reactions of ortho-amino derivatives of benzaldehyde with Meldrum"s acid, cyclohexane-1,3-dione, or N,N"-disubstituted barbituric acids.

Syntheses of new 1,2-azole-type fused heterocycles based on the α-pinene molecule are described.

Terpenic α-amino ketones have been prepared in good yield by treatment of the corresponding α-amino oximes with Ti(III) salts; all other known methods of deoximation give unacceptably low yields.

The treatment of 5-hydrazono-1,2,3-thiadiazoles by phosphorus pentachloride in toluene or xylene leads to an anomalous Dimroth rearrangement and the reaction of the mercapto function formed with the methyl group of the solvent to give 5-benzylmercapto-1,2,3-triazole.

The de novo production of the fungal metabolite, (+)-aristolochene by sporulated surface cultures of Penicillium roqueforti is reported for the first time. The biosynthesis of fungal volatiles by various sporulated surface cultures was monitored by solid phase micro-extraction (SPME). When comparing malt extract agar with sabouraud dextrose agar, the highest yield of the fungal metabolite (0.04 mg/ml of culture) was obtained with the latter medium. The biosynthesis of (+)-aristolochene showed a maximum during the fourth day after inoculation.

Reaction of (+)-3-carene trans-epoxide with sodium thiolates in methanolic solution in a microwave oven at 140 °C for 35–40 min affords corresponding (1S,3S,4S,6R)-4-sulfanylcaran-3-ols in 75–95% yields.

The treatment of (+)-3-carene nitrosochloride with 1,2-diaminoethane results in bis-α-aminoxime, which undergoes intramolecular cyclisation under phase-transfer conditions to yield an optically active macroheterocyclic compound with two carane moieties incorporated.

The title reaction resulted in N-alkyl imidazolyl derivatives 3 rather than isothiourea 2, and compounds 3 were transformed to imidazolylthiazoles 4 by the subsequent reaction with chloroacetone.

Reaction of arylpropargyl aldehydes with 2,3-dihydroxylamino-2,3-dimethylbutane results in the formation of 2-(1-hydroxy-4,4,5,5-tetramethylimidazolidin-2-ylidene)-1-arylethanones in high yields (70–80%). Allowing availability of propargyl aldehydes, this method gives new possibilities for the preparation of 2-(1-hydroxy-4,4,5,5-tetramethylimidazolidin-2-ylidene)-1-arylethanones.