Natural effectors of β-1,3-glucanases activator of the β-1,3-glucanases of marine mollusks

The capacity of certain extracts of marine invertebrates of the Indian and Pacific Oceans for activating -1,3-glucanases has been detected. It has been shown that an individual compound — swinholide A from the spongeTheonella swinhoei — specifically activates -1,3-glucanases of bivlve mollusks. In the presence of swinholide A both the hydrolysis of laminarin by -1,3-glucanase L-IV fromSpisula sachalinensis and the transglycosylation reaction are accelerated.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 316–320, May–August, 1992.     

Total Synthesis of (-)-α-Pinguisene

In previous work from our laboratory, we demonstrated that α-carbonyl radical cyclization reactions can serve efficiently as key steps in total synthesis of natural products.1 In this presentation,we report the total synthesis of (-)-α-pinguisene from enone 1 via α-carbonyl radical cyclization.     

Conversions of 2-α-chloroalkylbenzimidazoles

Upon interaction with caustic in a DMSO medium, 2-chloromethylbenzimidazoles are subjected to cyclodimerization, forming 5H,12H-pyrazino[1,2-a:4,5-a]bis-benzimidazoles; in the presence of nucleophiles (ammonia, amines, anions of -diketones), under the indicated conditions, the products are the corresponding substituted amines or derivatives of pyrrolo[1,2a]benzimidazole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 664–672, May, 1993.     

A Novel Synthesis of （-）-10-epi-a-Cyperone

An alternative route for the synthesis of (-)-10-epi-ct-cyperone 1 starting from ( )-dihydrocarvone 2 is described by using an asymmetric Michael addition as a key step. The routefeatures more efficiently and can be performed in large scale.     

Alkylation of 2,4-dimethylphenol with (+)-α- and (−)-β-pinenes in the presence of aluminum xylenolate

Alkylation of 2,4-dimethylphenol with (+)-α- and (?)-β-pinenes in the presence of aluminum 2,4-dimethylphenoxide generated in situ led to the formation of mixtures of products, from which optically active compounds were isolated. The structure of 2-bornyl-4,6-dimethylphenol was determined by X-ray analysis; its (+)- and (?)-enantiomers were assigned (1R,2R,4S) and (1S,2S,4R) configurations, respectively.     

Enantioconvergent Synthesis of (-)-α-Cuparenone Involving Chiral Inversion of a Ketone Intermediate

The acid (-)-2 was converted to the ketone (-)-6. Unsaturated ketone (+)-14 was synthesised from (-)-6. The ketone (+)-7 prepared from the acid (+)-3 on 1,2-ketone transposition, furnished the optical antipode (-)-6.     

Synthesis of Polyiodides of N- and S-S-Acetonyl Derivatives of 2,2′-(Disulfanediyl)- and 2,2′-[Alkanediylbis(sulfanyl)]-bisbenzimidazolium

Russian Journal of Organic Chemistry - 2,2′-(Disulfanediyl)- and 2,2′-[alkanediylbis(sulfanyl)]-bisbenzimidazoles react with aliphatic, aromatic, and heterocyclic α-iodoketones in...     

Reaction of aminals of conjugated unsaturated ω-dimethylaminoaldehydes with 1,2-, 1,3-, 1,4-, 1,5-, and 1,6-diketones

The condensation of aminals of -dimethylaminoacrolein and 5-dimethylaminopenta-2,4-dienal with cyclic and acyclic 1,2-, 1,3-, 1,4-, 1,5-, and 1,6-diketones was studied. A series of previously unknown bis(,-dimethylaminopolyenyl)diketones was synthesized; their structures were established by means of¹H and¹³C NMR spectroscopies. The electron absorption spectra were employed to study the mutual influence of -aminopolyene chromophores separated by two C=O groups.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1235–1241, July, 1993.     

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     

Kinetics of the Exothermic Decomposition Reaction of N-Methyl-N-nitro-2,2,2- trinitroethanamine

The thermal behavior and kinetic parameters of the exothermic decomposition reaction of N-methyl-N-nitro-2,2,2-trinitroethanamine in a temperature-programmed mode have been investigated by means of differential scanning calorimetry (DSC).The kinetic equation of the exothermic decomposition process of the compound is proposed. The values of the apparent activation energy (Ea), pre-exponential factor (A), entropy of activation (ΔS^≠ ), enthalpy of activation (ΔH^≠ ), and free energy of activation (ΔG^≠ ) of this reaction and the critical temperature of thermal explosion of the compound are reported. Information is obtained on the mechanism of the initial stage of the thermal decomposition of the compound.     

Synthesis and pesticidal activity of aminoesters of (+)-α-pinene

Optically active (\t-)-(1R,2R,3R) aminoesters of isopinocampheol (2,6,6-trimethylbicyclo[3.1.1]heptan-3-ol) were synthesized from (+)-α-pinene. The antifidant, juvenoidal, growth-regulating, and herbicidal activities of the newly synthesized compounds were studied. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 359–362, July–August, 2008.     

Synthesis of an analog of ( )-goniopypyrone from 3- O- benzyl-1,2- O-isopropylidene-5- C-phenyl-α-D-gluco-pentofuranose

8,9-Dimethoxy-7-epi-goniopypyrone, an analog of ( )-go-niopypyrone, was synthesized from 3-O-benzyl-1, 2-O-iso-propylidene-5-C-phenyl-α-D-gluco-pentofuranose (3).     

The First Example of 1,1-σ-Complexes of Phosphorus Nucleophiles

Abstract

We report on the first phosphorus 1,1-σ-complexes, relatively stable in DMSO. Adducts of this type are important as possible intermediates in nucleophilic aromatic substitution reactions but for phosphorus nucleophiles 1,1-σ-complexes were never detected [1]. We have found that interaction of 1 with 2 in DMSO leads initially to 1,3-σ-complexes 3 which slowly rearrange to 1,1-σ-complexes 4.     

Sonogashira reactions of α- and β-1-ethynyl-2-deoxyribosides: synthesis of acetylene-extended C-nucleosides

An improved practical protocol for the synthesis of both anomers of 1-ethynyl-2-deoxiribosides 1 was developed. The Sonogashira coupling of ethynyldeoxyribosides 1 with various aryl- and heteroaryl halides was carried out under various conditions. It was found that the use of copper-free coupling protocols could reduce the oxidative dimerisation in favour of arylalkynyldeoxyriboside formation.     

Total synthesis of(-)-goniopypyrone

Recently,three novel styryl-lactones,goniofufurone,goniopypyrone,and 8-acetylgo-niotriol,which are cytotoxic to human tumor cells,have been isolated from the stembark of Goniothalamus species.Amongst these lactones,goniopypyrone is the mostbioactive.Its unusual natural skeleton was revealed by X-rav structure analysis to be