Nucleophilic thiylation of limonene 8,9-oxide

Thioterpenols of the menthane series have been obtained by reactions of limonene 8,9-oxide with thiols and with isothiuronium salts.S. V. Kurashov Kazan' State Medical University, 420012, Kazan', ul. Butlerov, 49, Korp. B Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 197–200, March–April, 1999.     

New thioterpenoids based on carvone

Reactions of carvone with mercaptoacetic acid and its esters in the presence of ZnCl₂ were studied. New menthane-type thioterpenoids were produced. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 564–565, November–December, 2006.     

Selective synthesis of carvone and cryptomerlone from α-pinene

Carvone and cryptomerlone were synthesized selectively using electrochemical oxidation of α-pinene in the key step. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 248–250, May–June, 2006.     

Lead tetraacetate assisted formation of bis(acetoxy)acetic acid derivative from carvone

R-Carvone on heating with Pb(OAc)₄ in benzene gives (2RS)-2-hydroxy-2-[(1S)-4-methyl-5-oxocyclohex-3-en-1-yl)]-prop-1-yl bis(acetoxy)acetate. Alkaline hydrolysis of this compound affords the corresponding diol which under acidic catalysis is transformed into bis-hydroxy ether and 1,4-dioxane derivatives.     

Synthetic studies on the preparation of oxygenated spongiane diterpenes from carvone

The paper describes a new diastereoselective approach to oxygenated spongiane diterpenes functionally related to natural dorisenones. The strategy followed for the preparation of the spongiane framework, a B→AB→ABC→ABCD approach, is based on the preparation of epoxydecalone 11 (AB rings) from R-(−)-carvone, followed by an intramolecular Diels-Alder reaction for the construction of the C ring (compound 26). Further manipulation of the Diels-Alder adduct functionality allows the completion of the spongiane framework and the elaboration of several oxygenated spongiane-type compounds. The structures of two compounds 27 and 31, has been established by single-crystal X-ray crystallography.     

Antimicrobial activity of novel isothiuronium salts with 7-chloro-4,6-dinitrobenzofuroxan-5-olate anion

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Dynamic Covalent Chemistry of Nucleophilic Substitution Component Exchange of Quaternary Ammonium Salts

Dynamic covalent libraries (DCLs) of quaternary ammonium cations were set up by reversible nucleophilic substitution (S_N2′ and S_N2) exchange reactions of ammonium salts and tertiary amines. The reactions were conducted at 60 °C to generate thermodynamically and kinetically controlled mixtures of quaternary ammonium compounds and tertiary amines, and were accelerated by using iodide as a nucleophilic catalyst. Microwave irradiation was used to assist the exchange reaction between the pyridinium salts and pyridine derivatives. Finally, experiments towards the generation of dynamic ionic liquids were performed. The results of this study pave the way for the extension of dynamic combinatorial chemistry to nucleophilic substitution reactions.     

Unexpected Behavior of the Heaviest Halogen Astatine in the Nucleophilic Substitution of Aryliodonium Salts

Aryliodonium salts have become precursors of choice for the synthesis of ¹⁸F‐labeled tracers for nuclear imaging. However, little is known on the reactivity of these compounds with heavy halides, that is, radioiodide and astatide, at the radiotracer scale. In the first comparative study of radiohalogenation of aryliodonium salts with ¹²⁵I^? and ²¹¹At^?, initial experiments on a model compound highlight the higher reactivity of astatide compared to iodide, which could not be anticipated from the trends previously observed within the halogen series. Kinetic studies indicate a significant difference in activation energy (E_a=23.5 and 17.1 kcal mol^?1 with ¹²⁵I^? and ²¹¹At^?, respectively). Quantum chemical calculations suggest that astatination occurs via the monomeric form of an iodonium complex whereas iodination occurs via a heterodimeric iodonium intermediate. The good to excellent regioselectivity of halogenation and high yields achieved with diversely substituted aryliodonium salts indicate that this class of compounds is a promising alternative to the stannane chemistry currently used for heavy radiohalogen labeling of tracers in nuclear medicine.     

Photocyclization of carvone to carvone camphor using rare gas halide lasers

The intramolecular photocyclization of (-)carvone with rare gas halide lasers is decribed. A 70-fold increase in quantum yield is observed at an intensity of 60 MW/cm², which is rationalized in terms of consecutive two-photon absorption. The mechanism proposed also describes the product distribution, which is different from that obtained by lamp irradiation.     

The vinyl esters of phosphorus acids. 32. Phosphorus-containing isothiuronium salts

The vinyl esters of phosphorus acids containing an -chloromethylalkenyl substituent react readily with thiourea to form substituted phosphorylated S-isothiuronium chlorides, capable of being dialkylated to the corresponding internal salts (betaines). An allylic rearrangement was discovered for the first time in the series of substituted S-isopropenylisothiuronium salts. The anticholinesterase and toxicological characteristics of some of the obtained comopunds were measured and compared.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. 2, pp. 425–430, February, 1992.     

Heterogeneous acid-catalysed isomerization of carvone to carvacrol

Amberlyst 15 is an efficient solid acid catalyst for the aromatization of carvone into carvacrol without solvent in less than an hour. The catalyst is recycled twice and a continuous method is evaluated.     

Nucleophilic Vinyl Substitution in the Synthesis of Heterocycles. (Review)

Published data on the synthesis of various heterocyclic compounds by the reaction of nucleophiles with electrophilic olefins containing a nucleophilic group are reviewed and analyzed.     

Behavior of N,S-divinyl-2-mercaptobenzimidazole in the thiylation reaction

N,S-Divinyl-2-mercaptobenzimidazole reacts with thiols under free-radical initiation conditions at both vinyl groups to giveβ-addition products, whereas it reacts with sulfur dioxide to give a stable complex. N-Vinylbenzimidazole-2-thione was obtained by heating the divinyl derivative of benzimidazole-2-thione in the presence of a mercaptan without a catalyst. The former on reaction with thiols under the influence of azobisisobutyronitrile readily forms N-(β-alkylthio)ethylbenzimidazole-2-thiones; in the presence of ionic catalysts, N-(α-alkylthio)ethylbenzimidazole-2-thiones are formed.