Stereospecific formation of 7,8β-dihydroanalogs at the reduction of ponasterone acetonide with lithium in liquid ammonia

The reduction of ponasterone A diacetonide with lithium in liquid ammonia stereospecifically led to 7,8β-dihydroanalogs of 5α- and 5β-epimers of ponasterone A and 7,8β-dihydro-6α-hydroxy derivative. 7,8β-Dihydroponasterone A, phytoecdysteroid from the needles of Japanise yew Taxus cuspidata, and its 5α-epimer were synthesized.     

Triterpene glycosides from Astragalus and their genins. LXXVIII. Chemical transformation of cycloartanes. VI. Partial synthesis of cycloadsurgenina

Cycloadsurgenin, 20R,24 S-epoxycycloartan-6α,25-diol-3,16-dione, was partially synthesized in four steps from cyclosieversigenin. Side products with the structures 17E,24S-cycloart-17-en-6α,24,25-triol-3,16-dione and 17Z,24 S-cycloart-17-en-6α,24,25-triol-3,16-dione were obtained in addition to the desired product. Presented at the 1st International Symposim on Edible Plant Resources and the Bioactive Ingredients, Xinjiang, China, July 25–27, 2008. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 591–595, November–December, 2008.     

Triterpene glycosides from <Emphasis Type="Italic">Astragalus</Emphasis> and their genins. LXXXI. Chemical transformation of cycloartanes. VII. Synthesis of cyclosiversigenin lactone

The lactone 20R-25-norcycloartan-3β,6α,16β-triol-20,24-olide was synthesized from cyclosiversigenin. Presented at the 1st International Symposium on Edible Plant Resources and the Bioactive Ingredients, Xinjiang, China, July 25–27, 2008. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 324–327, May–June, 2009.     

Structure of iskenderolide

The structure of a sesquiterpene lactone germacranolide was defined as 1β,6β-dihydroxygermacr-4(5),10(14)-dien-8,12-olide and was the C₆-epimer of (11R)-11,13-dihydrotatridin-B.     

Synthesis of Aristotelia-Type Alkaloids. Part XV. Total synthesis of (+)-hobartinol

Synthetic (+)-makomakine ( 6 ) was transformed in six steps into (+)-17R,18R)-17,18-dihydrohobartine-17,18-diol ((+)- 5 ) with an overall yield of 38% (Scheme 2). This compound was shown to be identical with natural hobartinol, a monoterpene indole alkaloid from Aristotelia australasica, originally believed to be the (17S)-epimer 1 . At the same time, the synthesis of (+)- 5 delineates the hitherto unknown absolute configuration of this metabolite.     

Iridoids from <Emphasis Type="Italic">Symphoricarpos albus</Emphasis>

Twelve compounds including secologanin, loganin, the aglycon of loganin, and a new iridoid called glucologanin were isolated from fruit of common snowberry Symphoricarpos albus (L.) Blake. The structure of glucologanin was confirmed using PMR and mass spectroscopy and chemical transformations. 2′,3′,4′,6′,7-Penta-O-acetylloganin and 2′,3′,4′,6′-tetra-O-acetylloganin were synthesized. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 37–40, January–February, 2009.     

Synthesis,photochromism, and complex-forming ability of <Emphasis Type="Italic">p</Emphasis>-tosylaminobenzylideneaminospironaphthooxazine

New hybrid spirooxazine was synthesized from the 8′-amino-substituted spironaphtho-oxazine and 2-(p-tosylamino)benzaldehyde. Photochromism and the complex-forming ability toward Mg²⁺, Ba²⁺, La³⁺, and Tb³⁺ ions of the synthesized compound and initial 8′-amino-spironaphthooxazine were studied in comparison. The spectral kinetic differences in the photochromism and complex formation of these compounds were revealed.     

Synthesis and structure of 4′,4′-dimethyl[16α,17α]spiropentanopregn-4-ene-3,20-dione

4′,4′-Dimethyl[16α,17α]spiropentanopregn-4-ene-3,20-dione was synthesized. The addition of diazo-2,2-dimethylcyclopropane generated from N-(2,2-dimethylcyclopropyl)-N-nitrosourea to 16,17-didehydropregnenolone acetate occurs regio-and stereospecifically to give 3β-acetoxy-1′,1′-dimethyl-20-oxopregn-5-ene-[16α,17α;7′,6′]-4′, 5′-diazaspiro[2.4]-hept-4′-ene in high yield. Its thermolysis affords a spiropentane-containing steroid, which is transformed into the target diketone. The anti position of the gem-dimethyl group in the fused spiropentane fragment is evident from the X-ray diffraction study of the final product. Dedicated to Academician O. M. Nefedov on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2040–2042, November, 2006.     

N-substituted tetrahydro-1,3-oxazines and -oxazolidines. 2. Nitration of <Emphasis Type="Italic">N</Emphasis>-(ω-acylamino-β,β-dinitroalkyl)tetrahydro-1,3-oxazines and -oxazolidines

Nitration of N-(ω-acylamino0-β,β-dinitroalkyl)tetrahydro-1,3-oxazines and N-(ω-acylamino-β,β-dinitroalkyl)oxazolidines resulted in O-nitrates bearing amide, dinitromethylene, and nitroamine groups. It was found that nitration can be accompanied by N-hydroxymethylation of the amide group. Three nitrates synthesized were tested for, and exhibited good level of, cardioprotection.     

Triterpene glycosides of Thalictrum squarrosum. IV. Structures of squarrosides A1, A2, B1, and B2

Four new cycloartane glycosides have been isolated from a methanolic extract ofThalictrum squarrosum Stephan ex Willd.: squarroside A1 (I) — (21R, 22S, 23R)-3β-(β-D-glucopyranosyloxy)-21α-methoxy-21,23-epoxycycloart-24-ene-22β,30-diol, C₃₀H₆₀O₁₀; squarroside A2 (II) — the (21S)-epimer of compound (I); squarroside B1 (III) (21R, 22S, 23R)-3gb-[O-α-L-rhamnopyranosyl-(1 → 6)-β-D-glucopyranosyloxy]-21α-methoxy-21,23-epoxycycloart-24-ene-22β,30-diol, C₄₃H₇₀O₁₄; and squarroside B2 (IV) — the (21S)-epimer of compound (III). The proposed structures were determined on the basis of¹H and¹³C NMR spectroscopy, FAB mass spectrometry, and chemical transformations. Irkutsk Institute of Organic Chemistry, Siberian Branch, USSR Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 516–523, July–August, 1989.     

Synthesis of 5α-androstan-3β,17β-diol from tigogenin

5α-Androstan-3β,17β-diol (3b-adiol), a known inhibitor of prostate cancer cell growth, was synthesized from tigogenin. Its structure was confirmed by NMR and IR spectroscopy and mass spectroscopy. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 81–82, January–February, 2007.     

Chemical Constituents of Brown Rice Grain (<Emphasis Type="Italic">Oryza sativa</Emphasis>)

One new compound 3,7,11,15,19-pentamethyl-9α,10α,11α,17α,18α-pentahydroxy-n-tetracosan-1-oxy-p-hydroxycaffeoate (oryzaterpenyl caffeoate) (1), together with three known fatty acids linoleic acid, stearic acid and myristic acid were isolated and identified from the rice grain of Oryza sativa. The structure of the new compound was elucidated by 1D and 2D NMR spectroscopic techniques (¹H-¹HCOSY, ¹H-¹³C HETCOR) aided by EI-MS, and IR spectra. __________ Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 535–537, November–December, 2005.     

Syntheses based on norfluorocurarine. 2. Reduction and dehydrogenation products

The bisindole compound 2β,16α,2′β,16′β(H)-tetrahydronordihydrotoxiferine consisting of two diastereoisomeric deoxytetrahydronorfluorocurarine moieties was isolated from the reduction mixture of the alkaloid norfluorocurarine. 16-Deformyl-2,16,17,20-tetrahydro-20,21-dehydronorfluorocurarine was produced by dehydrogenation of norfluorocurarine; N(β)-methyldihydrodefluorocurarine, by hydrogenation of fluorocurarine. The structures of the synthesized compounds were established by x-ray structure analyses. The configurations of the asymmetric centers in 2β,16α,2′β,16′β(H)-tetrahydronordihydrotoxiferine were determined as 2S,3S,7R,15S,16R,2′S,3′S,7′R,15′S,16′S. Inversion to the R-configuration at the C15 center was observed in N(β)-methyldihydrodefluorocurarine whereas the configurations 3S and 7R were retained. Atom C2 adopted the S-configuration in 16-deformyl-2,16,17,20-tetrahydro-20,21-dehydronorfluorocurarine.     

Triterpene glycosides from <Emphasis Type="Italic">Astragalus</Emphasis> and their genins. LXXXV. Structure of cyclomacroside E

The structure of a new cycloartane-type triterpene glycoside, cyclomacroside E, which was isolated from roots of Astragalus macropus Bunge (Leguminosae), was established as 3-O-α-L-rhamnopyranoside,24-O[(β-D-xylopyranosyl)(1→2)-β-D-xylopyranoside]-24R-cycloartan-1α,3β,7β,24,25-pentaol.     

Triterpene glycosides from <Emphasis Type="Italic">Astragalus</Emphasis> and their genins. LXXXIX. Askendoside H from <Emphasis Type="Italic">Astragalus taschkendicus</Emphasis>

A new triterpene glycoside of the cycloartane series that was called askendoside H was isolated from roots of Astragalus taschkendicus Bunge (Leguminosae). Its structure was elucidated based on chemical transformations and spectral data. Askendoside H was a bisdesmoside of cycloorbigenin C, 23R,24Rcycloartan-3β,6α,16β,23,24,25-hexaol 3-O-[(α-L-arabinopyranosyl)(1 → 2)-β-D-xylopyranoside] 23-O-βD-glucopyranoside.     

Triterpene glycosides from <Emphasis Type="Italic">Astragalus</Emphasis> and their genins. LXXX. Cyclomacroside D,a new bisdesmoside

The structure of the new cycloartane glycoside cyclomacroside D, which was isolated from Astragalus macropus Bunge (Leguminosae) and is 24R-cycloartan-1α,3β,7β,24,25-pentaol 3-O-α-L-rhamnopyranoside–24-O-β-D-xylopyranoside, was proved. Presented at the 7th International Symposium on the Chemistry of Natural Compounds (SCNC, Tashkent, Uzbekistan, October 16–18, 2007). Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 48–50, January–February, 2009.     

Triterpene glycosides from <Emphasis Type="Italic">Astragalus</Emphasis> and their genins. XC. Askendoside K from <Emphasis Type="Italic">Astragalus taschkendicus</Emphasis>

A new triterpene cycloartane glycoside called askendoside K was isolated from roots of Astragalus taschkendicus Bunge (Leguminosae). The structure of this glycoside was established using chemical and biochemical transformations and spectral data. Askendoside K was a bisdesmoside of cycloorbigenin C and had the structure 23R,24R-cycloartan-3β,6α,16β,23,24,25-hexaol 3-O-[(α-L-arabinopyranosyl)(1 → 2)-β-D-xylopyranoside],23-O-[(β-D-glucuronopyranosyl)(1 → 2)-β-D-glucopyranoside].     

Triterpene glycosides from <Emphasis Type="Italic">Astragalus</Emphasis> and their genins. LXXXII. Cyclomacroside B,a new glycoside

The structure of the new cycloartane glycoside cyclomacroside B that was isolated from Astragalus macropus Bunge (Leguminosae) was shown to be 1,7-di-O-acetyl-24R-cycloartan-1α,3β,7β,24,25-pentaol 3-O-α-Lrhamnopyranoside-24-O-β-D-xylopyranoside.     

Triterpene glycosides from <Emphasis Type="Italic">Astragalus</Emphasis> and their genins. LXXXIII. Structure of cyclomacroside A

The structure of the novel cycloartane triterpene glycoside cyclomacroside A, which was isolated from Astragalus macropus Bunge (Leguminosae) roots, was determined as 3-O-α-L-rhamnopyranoside-24,25-isopropylidenedioxy-24R-cylcoartan-1α,3β,7β-triol.     

1,3-Dipolar cycloaddition reaction of heteroaromatic <Emphasis Type="Italic">N</Emphasis>-ylides with 3-[(<Emphasis Type="Italic">E</Emphasis>)-2-aryl(hetaryl)-2-oxoethylidene]indolin-2-ones

A series of 6a′,7′,8′,9′-tetrahydrospiro[indoline-3,7′-pyrrolo[1,2-a]quinoline]-2-one derivatives were synthesized by the 1,3-dipolar cycloaddition reaction. The regio-and stereoselectivity of the reaction were established by X-ray diffraction study. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2357–2361, October, 2005.