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.     

A new nine-membered lactone from a marine fungus Cladosporium sp. F14

A new nine-membered lactone, cladospolide E (1), was isolated from a culture broth of a marine fungus Cladosporium sp. F14. The structure of compound 1 was determined on the basis of extensive spectroscopic analysis, including 1D and 2D NMR data.       

Cationic copolymerization behavior of epoxide and 3‐isochromanone

Cationic copolymerization of n‐butyl glycidyl ether (BGE) and 3‐isochromanone (ICM) was investigated using trifluoromethanesulfonic acid (TfOH) as an initiator at 100 °C. In the copolymerization, the reactive site of ICM with the propagating cation was completely different from that in its homopolymerization: in the former, the propagating cation reacted with the carbonyl oxygen of ICM, while in the latter, the propagating cation reacted with the aromatic ring of ICM. In spite of the potential of ICM to undergo the homopolymerization, in the present copolymerization, ICM was consumed smoothly only in the presence of epoxide. As a result, the copolymerization proceeded in a statistic manner to afford the corresponding copolymer bearing ICM‐derived ester linkages distributed in the main chain. Cationic copolymerization of bisphenol A‐diglycidyl ether and ICM was also performed to synthesize the corresponding networked polymer. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4213–4220     

A New Sesquiterpene from the Roots of Lindera strychnifolia

The root of Lindera strychnifolia is used as a palliative and an antispasmodic in traditional chinese medicine. In previous studies of chemical constituents from this plant, more than 20 sesquiterpene lactones have been isolated and their structures were established1-7. In order to compare the difference of chemical constituents extracted by Supercritical Fluid Extraction (SFE) method and by organic solvent, the SFE extract from Lindera strychnifolia was investigated. A novel sesquiterp…     

Photochemistry of N-acetyl and N-benzoyl carbazoles: photo-Fries rearrangement and photoinduced single electron transfer

The photochemistry of two N-acyl carbazoles, N-acetyl and N-benzoyl carbazole, in different pure and mixed organic solvents is studied. Depending on the properties of the medium, photo-Fries rearrangement and photoinduced single electron transfer (PSET) processes are observed yielding the former 1-acyl and 3-acyl carbazoles and the latter 3-chloro-N-acyl carbazole. k_SV, k_Q and φ for fluorescence emission, conversion of N-acyl carbazole and product formation yields have been measured as well as the properties of the N-acyl carbazole radical cations formed during the PSET process (laser flash photolysis experiments). The Rehm-Weller equation is used in order to evaluate the ΔG°_ET of the PSET processes.     

Di-6R,7R1-4(3H)-Oxo-2-quinazolinyl-substituted Cyclobutanes from Pinic and sym-Homopinic Acids

The corresponding diamides were obtained from reaction of cis-3-carboxy-2,2-dimethylcyclobutylacetic acid (pinic acid) and of cis/trans-3-(carboxymethyl)-2,2-dimethylcyclobutylacetic acid (homopinic acid) dichlorides with two equivalents of 5-bromo-, 4-chloro-, and 4,5-dimethoxyanthranilic acids. Treatment of them with formamide leads to the formation of the corresponding 2,2-dimethyl-3-[4(3H)-oxo-2-quinazolinyl]methyl-1-[4(3H)-oxo-2-quinazolinyl]cyclobutanes and 2,2-dimethyl-1,3-di[4(3H)-oxo-2-quinazolinylmethyl]cyclobutanes.     

Synthesis of the four diastereoisomers of 3-thymine-1-(butoxycarbonyl)aminocyclopentane-1-carboxylic acid

Synthetic routes to all four diastereoisomers of 3-thymine-1-(^tbutoxycarbonyl)aminocyclopentane-1-carboxylic acid have been developed starting from the commercially available (S)-dimethyl malate. The key step in the synthesis involves dialkylation of N-(diphenylmethylene)glycine ethyl ester with 1,4-diiodo-2(S)-trityloxybutane.     

Asymmetric syntheses with catalytic enantioselective metal carbene transformations

Asymmetric catalysis of metal carbene transformations with unique chiral dirhodium(II) carboxamides provides highly enantioselective and diastereoselective synthesesvia cyclopropanation, cyclopropenation, and carbon-hydrogen insertion reactions of diazoesters and diazoamides. Constructed from a dirhodium(II) core with bridging pyrrolidone, oxazolidinone, or imidazolidinone ligands, these catalysts are especially effective for intramolecular transformations that occur in high yield with greater than 90 % enantiomeric excess (ee) and high diastereocontrol.Based on lectures given at the 1994 International INEOS Workshop, May 21–26, 1994, and at the Nesmeyanov Institute of Organoelement Compounds, Moscow, on May 30, 1994.On the occasion of the award of a D. Sc. (honoris causa) degree to Prof. M. P. Doyle for his works on catalytic enantioselective syntheses by the Russian Academy of Sciences in 1994.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1879–1892, November, 1994.     

Structures of 8α-(2′-methylbutyryloxy)-9α-hydroxymontahibisciolide,a new skeletal type of sesquiterpene lactone,and of its precursor 8α-isobutyryloxy-9-oxo-germacra-4E, 1(10)Z-dien-6β,12-olide

The structures of a new skeletal type of sesquiterpene lactone, containing a seven, five, fivering system, and of its putative precursor, a 9-oxo-melampolide, have been confirmed by single crystal X-ray structure determination. The central 5-membered ring of the new skeleton istrans-fused to the cycloheptene ring andcis-fused to the lactone ring. Transannular interactions and the geometry of thetrans carbon-carbon double bond of the oxo-melampolide and the keto-group at C9, suggest that the new seven, five, five tricyclic skeleton-type of montahibisciolide can easily be reached by a transannular cyclization process. The isobutyrloxy group of the oxo-melampolide is disordered into two partially populated conformations. 8-(2-Methylbutyryloxy)-9-hydroxymontahibisciolide,3, C₂₀H₂₈O₅, crystallizes in orthorhombic space groupP2₁2₁2₁ witha=8.294(2),b=9.740(2),c=22.675(1) Å,V=1832(1)ų,Z=4. The structure was refined toR=0.043 andR _w=0.048 for 2898 observed reflections with CuK radiation. 8-isobutyryloxy-9-oxo-germacra-4E, 1(10)Z-dien-6, 12-olide,4, C₁₉H₂₄O₅, crystallizes in monoclinic space groupC2 witha=32.879(7),b=5.793(2),c=9.884(4)Å, =99.01(3)°,V=1859.5(9)å³,Z=4. The structure was refined toR=0.054 andR _w=0.064 for 1010 observed reflections with MoK radiation.     

Samarium(III)‐mediated graft polymerization of ϵ‐caprolactone and L‐lactide on functionalized poly(p‐xylylene)s: model studies and polymerizations

The reductive coupling of aromatic monocarbonyl compounds in the presence of SmI₂ results in the formation of Samarium(III) dialkoxides. These Sm(III) dialkoxides have been utilized as initiators for ring opening polymerization (ROP) of lactones and lactides. The reductive coupling of aromatic dicarbonyl compounds results in the formation of Sm(III) polyalkoxides which have been used as polyinitiator for (ROP) of lactones and lactides. The products of this process are poly(p‐xylylene)s grafted by polylactones or polylactides. Grafting efficiency depends significantly on reaction conditions and is currently limited to 28%. Copyright © 1999 John Wiley & Sons, Ltd.