9(11)-dehydroagapanthagenin,a new spirostan sapogenin from Agapanthus africanus

The structure of 9(11)-dehydroagapanthagenin, a new spirostan sapogenin isolated from the rhizomes of Agapanthus africanus, was determined on the basis of spectral and chemical evidence.     

Microbial oxygenation of dialkylbenzenes (I)

The use of the microorganism Sporotrichum sulfurescens (ATCC 7159) to oxygenate organic molecules has been extended to several dialkylbenzenes. Oxygenation of 1,4-di-t-butylbenzene (1) gave 4-t-butyl(1-hydroxy-2-methyl)isopropylbenzene (2) and 1,4-di-(1-hydroxy-2-methyl)isopropylbenzene (3); of 1,4-diisopropylbenzene (4) gave (R,R)-1,4-di-(1-hydroxy)isopropylbenzene (5); of 1,3-diisopropylbenzene (6) gave 1,3-di-(2-hydroxy)isopropylbenzene (7), 3-(1-hydroxy)isopropyl-(2-hydroxy)isopropylbenzene (8), and 1,3-di-(1-hydroxy)isopropylbenzene (9); and of p-isobutylisopropylbenzene (20) gave 1-(p-2-hydroxyisopropylphenyl)-2-methylpropan-2-ol (15) and 1-(p-1-hydroxyisopropylphenyl)-2-methylpropan-2-ol (16). Monohydroxydialkylbenzenes also served as useful substrates in this reaction as suggested by the fact that 2 is an intermediate in the formation of 3 from 1. Oxygenation of 1-(p-isopropylphenyl)-2-methylpropan-2-ol (14), conveniently prepared from 2-(p-isopropylphenyl)propene (12) via oxygenative isomerization with thallium trinitrate to 13 followed by addition of methyl magnesium bromide, gave 15 and 16. Oxygenation of 2-(p-isobutylphenyl)propan-2-ol (18) gave 15, 2-(p-isobutylphenyl)-propan-1,2-diol (21), and 1-(p-2-hydroxyisopropylphenyl)-2-methylpropan-3-ol (22). Compound 16, obtained from substrate 14, was converted to (2R)-2-[4-(2-hydroxy-2-methylpropyl)phenyl]propionic acid (11), the enantiomer of a metabolite of the antiinflammatory agent, 2-(4-i-butyl)phenylpropionic acid (10).     

Angkorensides A and B – Two anti-inflammatory acyl glycosides from Gardenia angkorensis

Two new acyl glycosides, angkorensides A and B (1 and 2) together with twelve known compounds including hedyotol C 7″-O-β-D-glucopyranoside (3), proanthocyanidin A-1 (4), (-)-epicatechin (5), (+)-lyoniresinol 3α-O-β-D-glucopyranoside (6), kaempferol-3-O-β-D-galactopyranoside (7), cuneataside E (8), 4-hydroxyacetophenone 4-O-(6′-O-β-D-apiofuranosyl)-β-D-glucopyranoside (9), cinnamtannin B-1 (10), aesculitannin B (11), quercetin 3-O-rham-(1−6)-β-D-galactopyranoside (12), quercetin 3-O-β-D-galactopyranoside (13), and proanthocyanidin A-2 (14) have been unprecedentedly isolated from Gardenia angkorensis Pit. Angkorensides A and B (1 and 2) showed moderate anti-inflammatory inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 macrophages and the known compounds (4, 10-14) exhibited strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity.     

Flavonoids and phenolic acids from the aerial parts of Alyssum alyssoides L. (Brassicaceae)

Two phenolic acids (1 and 2) and seven flavonoids (3–9) were isolated from the aerial parts of Alyssum alyssoides (Brassicaceae). All these compounds (1–9) were isolated from this particular species for the first time. Their structures were identified, on the basis of MS and NMR spectra as: p-hydroxy-benzoic acid (1), 3-methoxy-4-hydroxybenzoic acid (vanillic acid) (2), kaempferol 3-O-β-D-glucopyranoside (astragalin) (3), kaempferol 3-O-(6″-α-L-rhamnopyranosyl)-β-D-glucopyranoside (nicotiflorin) (4), quercetin 3-O-β-D-glucopyranoside (isoquercetin) (5), quercetin 3-O-β-D-galactopyranoside (hyperoside) (6), isorhamnetin 3-O-β-D-glucopyranoside (7), isorhamnetin 3-O-β-D-galactopyranoside (8) and isorhamnetin 3-O-(6″-α-L-rhamnopyranosyl)-β-D-glucopyranoside (narcissin) (9). The chemotaxonomic significance of these compounds was summarized.     

Investigation of C-5 alkynyl (alkynyloxy or hydroxymethyl) and/or N-3 propynyl substituted pyrimidine nucleoside analogs as a new class of antimicrobial agents

The resurgence of mycobacterial infections and the emergence of drug-resistant strains urgently require a new class of agents that are distinct than current therapies. A group of 5-ethynyl (6–10), 5-(2-propynyloxy) (16, 18, 20, 22, 24), 5-(2-propynyloxy)-3-N-(2-propynyl) (17, 19, 21, 23, 25) and 5-hydroxymethyl-3-N-(2-propynyl) (30–33) derivatives of pyrimidine nucleosides were synthesized and evaluated against mycobacteria [Mycobacterium tuberculosis (Mtb), Mycobacterium bovis (BCG) and Mycobacterium avium], gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis) and gram-negative bacteria (Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa) alone and in combination with existing drugs in in vitro assays. Although several compounds exhibited marked inhibitory activity at a higher concentration against Mtb, M. bovis, S. aureus and E. faecalis, they displayed unexpected synergistic and additive interactions at their lower concentrations with antitubercular drugs isoniazid and rifampicin, and antibacterial drug gentamicin. The active analogues were also found to inhibit intracellular Mtb in a human monocytic cell line infected with H37Ra. Oral administration of 5-hydroxymethyl-3-N-(2-propynyl)-3′-azido-2′,3′-dideoxyuridine (32) and 5-hydroxymethyl-3-N-(2-propynyl)-2′,3′-dideoxyuridine (33) at a dose of 100 mg/kg for two weeks showed promising in vivo effects in mice infected with Mtb (H37Ra). No in vitro cytotoxicity of the test compounds was observed up to the highest concentration tested (CC50 > 300 μg/mL).     

Derivatives of phosphonate and vinyl phosphate analogs of D-ribose 5-phosphate

Propanal thiosemicarbazone (1a) showed activity in preventing anaphylactic shock in a mouse test-system; it also had some activity in stunting the growth of Botrytis allii. Hexanal thiosemicarbazone (1b) was active in the Botrytis allii test-system, and citral thiosemicarbazone (2) and citral guanylhydrazone nitrate (3) showed some activity in the same test-system. Heptanal guanylhydrazone nitrate (4) had some antibacterial activity against Staphylococcus aureus, and D-threo-pentosulose bis(thiosemicarbazone) (5) prevented anaphylactic shock in the mouse test-system. D-glycero-Tetrosulose bis(thiosemicarbazone) (6), D-lyxo-hexosulose bis-(guanylhydrazone) nitrate (7), D-galacto-heptosulose bis(thiosemicarbazone) (8), and D-galacto-heptosulose bis(guanylhydrazone) sulfate (9) showed some activity in stunting the growth of Botrytis allii. The copper chelate (10a) of D-arabino-hexosulose bis(thiosemicarbazone), and the copper (11a) and palladium (11b) chelates of 6-deoxy-L-arabino-hexosulose bis(thiosemicarbazone) showed antitumor activity in the KB cell-culture test-system. The palladium chelate 11b also showed some activity in the leukemia p-388 mouse test-system.     

Acylated hydroxycinnamic acid glucosides from flowers of Telekia Speciosa

One new derivative of ferulic acid (1), two new caffeic acid derivatives (2 and 3) and three known derivatives of caffeic acid: 6-O-(E)-caffeoyl-glucopyranose (4), (E)-caffeic acid 4-O-β-glucopyranoside (5) and 5-caffeoylquinic acid (chlorogenic acid, 6) were isolated from a butanolic fraction of extract from Telekia speciosa flowers. Moreover, the flavonol glucoside–patulitrin (7) was identified in the analyzed extract. Structures of (E)-ferulic acid 4-O-β-(6-O-2-hydroxyisovaleryl)-glucopyranoside (1), (E)-caffeic acid 4-O-β-(6-O-2-hydroxyisovaleryl)-glucopyranoside (2) and (E)-caffeic acid 4-O-β-(6-O-3-hydroxy-2-methylpropanoyl)-glucopyranoside (3) were elucidated by 1D and 2D NMR, HRESIMS and other spectral analyses.     

Fatty acid derivatives and dammarane triterpenes from the glandular trichome exudates of Ibicella lutea and Proboscidea louisiana

Ibicella lutea and Proboscidea louisiana, both of the Martyniaceae family, are known for rich glandular trichomes on their leaves and stems. Chemical investigations of the glandular trichome exudates on leaves of the two plants furnished three types of secondary metabolites, glycosylated fatty acids, glycerides (2-O-(3,6-diacetyloxyfattyacyl)glycerols and 2-O-(3-acetyloxyfattyacyl)glycerols) and dammarane triterpenes. The glycosylated fatty acids from I. lutea were determined to be 6(S)-(6-O-acetyl-β-d-glucopyranosyloxy)-octadecanoic acid (1A), -eicosanoic acid (1B) and -docosanoic acid (1C), as well as their respective deacetyl congeners (2A, 2B and 2C), whereas P. louisiana furnished 8(S)-(6-O-acetyl-β-d-glucopyranosyloxy)-eicosanoic acid (3A) and -docosanoic acid (3B) and their respective deacetyl congeners (4A and 4B), together with 2B. Both plants contained 12 identical 2-O-[(3R,6S)-3,6-diacetyloxyfattyacyl]glycerols (5A-L), in which the fatty acyl moieties contained between 17 and 21 carbon atoms. The corresponding mono-acetyloxy compounds, 2-O-[(3R)-3-acetyloxyfattyacyl]glycerols (6A–L) were detected in both plants. Among these glycerides, ten compounds (5A, 5C, 5F, 5H, 5K, 6A, 6C, 6F, 6H and 6K) had iso-fattyacyl structures and four (5E, 5J, 6E and 6J) had anteiso-fattyacyl structures. A previously unknown dammarane triterpene, betulatriterpene C 3-acetate (7), was isolated together with three known dammarane triterpenes, 24-epi-polacandrin 1,3-diacetate (8), betulatriterpene C (9) and 24-epi-polacandrin 3-acetate (10) from I. lutea, whereas 12 dammarane triterpenes, named probosciderols A–L (12–23), and the known compound betulafolienetriol (11) were isolated from P. louisiana. The structures of these compounds were elucidated by spectroscopic analysis including 2D-NMR techniques and chemical transformations. The 6-O-acetylglucosyloxy-fatty acids 1A–C (42%) and the dammarane triterpenes 7–10 (31%) were the two most abundant constituents in the glandular trichome exudate of I. lutea, whereas the dammarane triterpenes 11–23 (47%) and the glucosyloxy-fatty acids (4A, 4B and 2B) (38%) were the most abundant constituents in the glandular trichome exudate of P. louisiana.     

Stereospecific synthesis of chiral benzylic centers from D-erythro-pentulose derivatives

Stereospecific, Grignard addition reactions are described that afford C-phenyl branched-chain pentitols having either the D-arabino(2) or D-ribo(19) stereochemistry, according to the mode of substitution of the starting 2-pentulose. The reaction of 3,5-O-benzylidene-1-deoxy-D-erythro-2-pentulose (1) with phenyl-magnesium bromide led stereospecifically to 3,5-O-benzylidene-1-deoxy-2-C-phenyl-D-arabinitol (2), the configuration of which was established by a nuclear Overhauser experiment with its 2,4:3,5-dibenzylidene acetal (3). Acid hydrolysis of 2 led to the novel, crystalline 1-deoxy-2-C-phenyl-D-arabinitol (4), further characterized as its triacetate 5. In attempts to mask certain hydroxyl groups of 2 selectively, the 2,4-O-isopropylidene (6) and 2,4-O-carbonyl (7) derivatives, the 4-acetate 8, the 4-(trimethylsilyl) and 4-(tert-butyldimethylsilyl) ethers (10 and 17), and the corresponding 2-phenylcarbamates 9 (from 8) and 11 (from 10) were prepared. Catalytic hydrogenolysis of the carbamates 9 and 11 resulted in deoxygenation of the benzylic center with inversion of configuration to give 2(S)-3,5-O-benzylidene-1,2-dideoxy-2-C-phenyl-D-erythro-pentitol (12; from 11) and its 4-O-acetyl analog 13 (from 9). Benzylation of the trimethylsilyl ether 10 afforded 2-O-benzyl-3,5-O -benzylidene-1-deoxy-2-C-phenyl-4-O-(trimethylsilyl)-D-arabinitol (15), together with the corresponding 2,4-dibenzyl ether 14. Acid hydrolysis of 15 yielded the crystalline, branched-chain, benzyl ether 16. The tert-butyldimethylsilyl ether of 1 reacted with phenylmagnesium bromide to give, exclusively, the C-phenyl branched-chain pentitol (19) having the D-ribo stereochemistry.     

Antimicrobial terpenoids of Gossypium: Hemigossypol, 6-methoxyhemigossypol and 6-deoxyhemigossypol

The sesquiterpenoid aldehydes, hemigossypol (1a), 6-methoxyhemigossypol (1b), and 6-deoxyhemigossypol (1c), were isolated and identified from Verticillium-infected stele tissue of Gossypium barbadense. Structures were established by spectral (UV, IR, NMR, MS) evidence and chemical transformations. This is the first report of (1b) and (1c) in nature, and of NMR and m.p. data for crystalline pure (1a). Compound (1a) occurred in diseased stele tissues of all 21 Gossypium species examined and in the genera, Cienfuegosia, Gossypioides, Hampea, and Thespesia; it was absent in three Hibiscus spp. Compound (1b) occurred in the same taxa as (1a), except that it was absent in species of two cytogenetic groups (A and B genome) of Gossypium. Compound (1c) occurred in trace quantities, or was not detected, in most species; however, its distribution appeared to besimilar to that     

Crystal structures of three thiourea (tu) complexes of Pt(II): trans-[(tu)2Pt(NH3)2]Cl2, trans-[(tu)2Pt(CH3NH2)2]Cl2·3H2O and [Pt(tu)4]Cl2

The structures of three Pt(II) thiourea complexes, trans-[(tu)₂Pt(NH₃)₂]Cl₂ (1), trans-[(tu)₂Pt(CH₃NH₂)₂]Cl₂·3H₂O (2) and [Pt(tu)₄]Cl₂ (3), have been determined by X-ray diffraction and refined to R = 0.049 for 1026 reflections (1), R = 0.057 for 2547 reflections (2) and R = 0.046 for 2792 reflections (3). All the compounds crystallize in the space group P2₁/c and have cell dimensions: a = 5.437(1), b = 6.450(1), c = 17.980(3) Å, β = 96.05(2)°, Z = 2 (compound 1); a = 9.225(1), b = 15.404(2), c = 12.601(2) Å, β = 105.39(2)°, Z = 4 (compound 2); and a = 9.051(6), b = 10.203(6), c = 18.263(8) Å, β = 91.12(8)°, Z = 4 (compound 3). The unit cell of 1 and 3 contains only a single type of cation, while that of 2 is formed from two independent cations. In 1 and 2 the coordination spheres of the Pt atoms are rather similar, with angles close to 90° and coplanarity of the metal and respective donor atoms. Instead, in 3 the four sulfur atoms, which surround the Pt, display a slight distortion (0.06 Å from the mean plane) towards tetrahedral.     

Cytotoxic quinazoline alkaloids from the seeds of Peganum harmala

Seventeen quinazoline alkaloids and derivatives, containing two pairs of new epimers, named as (S)- and (R)-1-(2-aminobenzyl)-3-hydroxypyrrolidin-2-one β-d-glucopyranosyl-(1?→?6)-β-d-glucopyranoside (1, 2), (S)- and (R)-vasicinone β-d-glucopyranosyl-(1?→?6)-β-d-glucopyranoside (3, 4), and a new enantiomer (12b), together with six known ones (5–8, 10, and 12a), and three pairs of known enantiomers (9, 11, and 13), were isolated from the ethanol extracts of the seeds of Peganum harmala L.. Their structures including the absolute configuration were elucidated by using 1D and 2D NMR, and ECD calculation approaches. The cytotoxic activities of all isolated compounds were evaluated. 11 showed moderate cytotoxicity against PC-3 cells with an IC₅₀ value of 15.41?μM.     

Synthesis and cytokinin activity of N-acylaminodeazapurines

Three 7-acylaminoimidazo[4,5-b]pyridines, namely 7-pentanoylaminoimidazo[4,5-b]pyridine (1), 7-benzoylaminoimidazo[4,5-b]pyridine(2), and 7-(2-furoylamino)imidazo[4,5-b]pyridine(3), six 4-acylaminoimidazo[4,5-c]pyridines, namely 4-propionylaminoimidazo[4,5-c]pyridine(4), 4-butyryl-aminoimidazo[4,5-c]pyridine(5), 4-pentanoylaminoimidazo[4,5-c]pyridine(6) 4-hexanoylaminoimidazo[4,5-c]pyridine(7),4-benzoylaminoimidazo[4,5-c]pyridine(8), and 4-(2-furoylamino)imidazo[4,5-c]-pyridine(9), and seven 7-acylaminoimidazo[4,5-c]pyridines, namely 7-propionylaminoimidazo[4,5-c]-pyridine(10), 7-butyrylaminoimidazo[4,5-c]pyridine(11), 7-pentanoylaminoimidazo[4,5-c]pyridine(12), 7-hexanoylaminoimidazo[4,5-c]pyridine(13), 7-benzoylaminoimidazo[4,5-c]pyridine(14), 7-phenylacetylaminoimidazo[4,5-c]pyridine(15), and 7-(2-furoylamino)imidazo[4,5-c]pyridine(16) were synthesized and tested for their cytokinin activity with the tobacco callus bioassay. 2 showed a cytokinin activity at 1 × 10⁻⁸ M and gave a callus yield about 72% of that produced by kinetin at 1 × 10⁻⁶ M. 1, 3 and 8 showed the optimum growth responses in the range of 10⁻⁷−10⁻⁶ M. 4, 5, 7, 9–16 were slightly active. These results support previous reports that a nitrogen atom at the 3-position in the purine ring plays an important role in conferring high cytokinin activity.     

Chemical constituents from the roots of Fallopia multiflora var. Ciliinerve

Phytochemical investigations on the roots of Fallopia multiflora var. Ciliinerve led to the isolation of eighteen compounds, including six chromones [2-methyl-5- carboxymethyl-7-hydroxychromone (1), 2-methyl-5-methylcarboxymethyl-7- hydroxychromone (2), 2,5-dimethyl-7-hydroxychromone (3), 2-methyl-5-hydroxymeth-yl-7-hydroxychromone (4), 2-methyl-5-carboxylicacid-7-hydroxy-chromone (5), and 2,5-dimethyl-7-hydroxychromone-7-O-β-D-glucopyranoside (6)], three lignans [Isolariciresinol (8), 5-[4-(3,4-dimethoxyphenyl)-2,3-dimethylbutyl]-1,3-benzodioxole (9), and isolariciresinol-9-O-β-D-xylopyranoside (10)], four anthraquinones [physcion-8-O-β-D-glucopyranoside (11), emodin-8-O-β-D-glucopyranoside (12), Rhein (13), and Chrysophanol (14)], three isobenzofurans [5,7-dihydroxy-isobenzofuran (15), 5-methoxy-7-hydroxy-isobenzofuran (16), and 5-methoxy-isobenzofuran-7-O-β-D-glucoside (17)], one phenolic acid [2,5-diacethylhy-droquinone (7)], and one pyran [Zanthopyranone (18)]. Among them, compounds 1, 3, 6, 13 and 14 were reported from F. multiflora var. Ciliinerve for the first time, compounds 2, 8, 10 and 15–17 were isolated from the genus Fallopia for the first time, and compounds 4, 9 and 18 were isolated for the first time from Polygonaceae family. Furthermore, the isolation of compounds 5 and 7 were reported for the first time in plants. Their structures were identified by spectroscopic methods and compared with those previously published. The chemotaxonomic significance of these isolated compounds has also been discussed.     

Reactions of carbohydrate α-nitroepoxides with dimethylamine and with methylmagnesium iodide

Methyl 2,3-anhydro-4,6-O-benzylidene-3-C-nitro-β-d-allopyranoside (1), as well as its β-d-manno (2) and α- d-manno (3) isomers, reacted with dimethylamine to give the same, crystalline 3-(dimethylamino) adduct (4) of 1,5-anhydro-4,6-O-benzylidene-2-deoxy-2-(dimethylamino)-d-erythro-hex-1-en-3-ulose (5). The enulose 5 was obtained from 4 by the action of silica gel. Similarly, the β-d-gulo (6) and α-d-talo (7) stereoisomers of 1–3 afforded a 3-(dimethylamino) adduct (8) of the d-threo isomer (9) of 5. Reaction of dimethylamine with 5,6-anhydro-1,2-O-isopropylidene-6-C-nitro-α-d-glucofuranose (10) yielded a mixture of two diastereoisomeric (possibly anometic at C-6) 5-deoxy-5-(dimethylamino)-1,2-O-isopropylideric-α-d-hexodialdo-1,4:6,3-difuranoses (11). The β-glycoside 1 and the α-glycoside 3 reacted with methylmagnesium iodide to produce methyl 4,6-O-benzylidene-3-deoxy-3-C-methyl-3-(N-hydroxy-N-methylamino)-β- and -α-d-hexopyranosides (12) and (13), respectively; both products had the 1,2-trans configuration, but their configurations at the quaternary center C-3 have not been determined.     

Structural features of group V A xanthates. The crystal and molecular structures of tris(O-isopropylxanthatoarsenic(III), antimony(III) and -bismuth(II)

The crystal structures of the title compounds, M(S₂COⁱC₃H₇)₃, M = As(III), (1); Sb(III), (2); and Bi(III), (3) have been determined by three dimensional X-ray diffraction techniques and refined by a least square method. Crystals of (1) and (2) are isomorphous and both crystallize in the rhombohedral space group R$\text{3}$, with unit cell parameters for (1) a_hex = 11.559(2), c_hex = 28.131(3) Å and for (2) a_hex = 11.696(2) and c_hex = 28.135(2) Å, Z = 6. The central metal atom in both (1) and (2) is coordinated by three asymmetrically chelating xanthate ligands [AsS 2.305(2) and 2.978(2) Å and SbS 2.508(1) and 3.006(1) Å] which form a distorted octahedral environment consistent with the presence of a stereochemically active lone pair of electrons. Crystals of (3) are orthorhombic, space group Pnma, Z = 4 with dimensions a = 11.003(3), b = 20.833(4) and c = 9.428(2) Å. The environment of the bismuth atom in (3) is seven coordinate and is comprised of six sulphur atoms, derived from three asymmetrically coordinating xanthate ligands, and a bridging sulphur atom from a neighbouring molecule which results in the formation a polymeric array. For (1) final R and R_W 0.050 and 0.047 respectively for 936 reflections [I ? 3σ(I); (2) R 0.040, R_w 0.040 for 1455 reflections I ? 2σ(I)]; and (3) R 0.052, R_w 0.039 for 1796 reflections [I ? 2σ(I).     

Photochemical addition of 1,3-dioxolane and of 2-propanol to 1,2,4,6-tetra-O-acetyl-3-deoxy-α- and -β-D-erythro-hex-2-enopyranose

Photoirradiation of a solution of 1,2,4,6-tetra-O-acetyl-3-deoxy-β-D-erythro-hex-2-enopyranose (1) in 1:50 acetone-1,3-dioxolane with a high-pressure mercury-lamp, followed by chromatographic separation, gave 1,2,4,6-tetra-O-acetyl-3-deoxy-3-C-(1,3-dioxolan-2-yl)-β-D-glucopyranose (3) (44%) and-mannopyranose (4) (35%). Similar treatment of the α anomer (2) of 1 afforded 1,2,4,6-tetra-O-acetyl-3-deoxy-3-C-(1,3-dioxolan-2-yl)-α-D-glucopyranose (5) (38%), -mannopyranose (6) (31%), and -allopyranose (7) (21%).On the other hand, irradiation of 2 in 1:100 acetone-2-propanol gave 1,2,4,6-tetra-O-acetyl-3-deoxy-3-C-(1-hydroxy-1-methylethyl)-α-D-mannopyranose (8) (76%). Moreover, irradiation of 2 in 1:1 acetone-2-propanol yielded 1,4,6-tri-O-acetyl-3-deoxy-2,3-di-C-(1-hydroxy-1-methylethyl)-α-D-gluco- or -manno-pyranose 2,2¹,3¹-orthoacetate (10) (15%), in addition to 8 (44%).     

Chemotaxonomic significance of lindenane sesquiterpenoid dimers and eudesmane sesquiterpenoids from Chloranthus henryi Hemsl. var. hupehensis (Pamp.) K. F. Wu

Seventeen known compounds were isolated from the 95% alcohol extract of the aerial parts of Chloranthus henryi Hemsl. var. hupehensis (Pamp.) K. F. Wu, including five lindenane sesquiterpenoid dimers (1–5) and twelve eudesmane sesquiterpenoids (6–17). In the present research, compounds 3 sarcaglabrin C, 6 neolitacumone C, 7 ent-Atractylenolide III and 8 dehydrocarissone were reported from the Chloranthus genus for the first time, and compounds 1 spicachlorantin B, 2 chloramultilide C, 4 shizukaol B, 5 japonicone C, 9 6α-hydroxyeudesma-4(15),7(11),8(9)-triene-12,8-olide, 10 ent-(3R)-3-hydroxyatractylenolide III, 11 8βH-hydroxyeudesma-4(14),7(11)-dien-12,8-olide, 12 lasianthuslactone A, 13 (5S,6R,8S,10R)-6-hydroxyeudesma-4(15),7(11)-diene-12,8-olide, 14 4β-hydroxy5α,8β(H)-eudesm-7(11)-en-8,12-olide, 15 4β,8β-dihydroxy-5α(H)-eudesm-7(11)-en-8,12-olide, 16 curcolonol and 17 1β, 8β-dihydroxyeudesm - 3,7(11)-dien-8α,12-olide were firstly isolated from the plant. Their structures were elucidated on the basis of extensive spectroscopic and chemical analyses. Moreover, the chemotaxonomic significance of the isolated compounds is discussed.     

Acetonation of d-ribose and d-arabinose with alkyl isopropenyl ethers

d-Ribose (1) in N,N-dimethylformamide containing a trace of p-toluenesulfonic acid is acetonated under kinetic control by ethyl (or methyl) isopropenyl ether (2) to give mainly 3,4-O-isopropylidene-β-d-ribopyranose (3), together with lesser proportions of 2,3-O-isopropylidene-d-ribofuranose (4), its 5-(2-alkoxy-2-propyl) ether (5 or 5a), and 1,5:2,3-di-O-isopropylidene-β-d-ribofuranose (6). Similar treatment of d-arabinose (10) gives mostly 3,4-O-isopropylidene-β-d-arabinopyranose (11) together with a minor proportion of 1,2:3,4-di-O-isopropylidene-β-d-arabinopyranose (12). The strucutres of the monoacetals 3 and 11 were confirmed by an acetylation-deacetonation-acetylation sequence.     

Synthesis of acetylenic sugars and uronic acids via two-carbon chain extension of d-ribose

Treatment of methyl β-d-ribofuranoside with acetone gave methyl 2,3-O-isopropylidene-β-d-ribofuranoside (1, 90%), whereas methyl α-d-ribofuranoside gave a mixture (30%) of 1 and methyl 2,3-O-isopropylidene-α-d-ribofuranoside (1a). On oxidation, 1 gave methyl 2,3-O-isopropylidene-β-d-ribo-pentodialdo-1,4-furanoside (2), whereas no similar product was obtained on oxidation of 1a. Ethynylmagnesium bromide reacted with 2 in dry tetrahydrofuran to give a 1:1 mixture (95%) of methyl 6,7-dideoxy-2,3-O-isopropylidene-β-d-allo- (3) and -α-l-talo-hept-6-ynofuranoside (4). Ozonolysis of 3 and 4 in dichloromethane gave the corresponding d-allo- and l-talo-uronic acids, characterized as their methyl esters (5 and 6) and 5-O-formyl methyl esters (5a and 6a). Ozonolysis in methanol gave a mixture of the free uronic acid and the methyl ester, and only a small proportion of the 5-O-formyl methyl ester. Malonic acid reacted with 2 to give methyl 5,6-dideoxy-2,3-O-isopropylidene-β-d-ribo-trans-hept-5-enofuranosiduronic acid (7).