Search results for "lactone"
showing 10 items of 335 documents
Diene/polar monomer copolymers, compatibilisers for polar/non-polar polymer blends. A controlled block copolymerisation with a single-site component …
2002
A well-controlled two-step process, the polymerisation of isoprene or isoprene/hex-1-ene copolymerisation followed by e-caprolactone polymerisation, affords trans-polyisoprene or (trans-polyisoprene/hex-1-ene copolymer)–poly(e-caprolactone) diblocks of various lengths. The single component initiator is an allylsamarocene compound. An atomic force microscopy study shows that these copolymers are efficient compatibilisers for poly(e-caprolactone) and polyisoprene blends. Poly(e-caprolactone) chain growth from Sm–polyisoprene chain.
Performance of polyester-based electrospun scaffolds under in vitro hydrolytic conditions: From short-term to long-term applications
2019
The evaluation of the performance of polyesters under in vitro physiologic conditions is essential to design scaffolds with an adequate lifespan for a given application. In this line, the degradation-durability patterns of poly(lactide-co-glycolide) (PLGA), polydioxanone (PDO), polycaprolactone (PCL) and polyhydroxybutyrate (PHB) scaffolds were monitored and compared giving, as a result, a basis for the specific design of scaffolds from short-term to long-term applications. For this purpose, they were immersed in ultra-pure water and phosphate buffer solution (PBS) at 37 °
High-Yield Synthesis of 20-, 24-, and 28-Membered Macropentolide, -hexolide, and -heptolide, Respectively, from (R)- or (S)-3-hydroxybutanoic acid un…
1988
The macrocyclic pentolide 1, hexolide 2, and heptolide 3 constitute ca. 80% of the oligomers formed in ca. 50% yield from enantiomerically pure 3-hydroxybutanoic acid under Yamaguchi's macrolactonization conditions. The FAB mass spectra of the MH+, M Na+, and MCs+ are reported (Figs. 2, 3, 5, and 6). No cyclic tetramer is detected. The 1H-NMR spectra of the cyclic oligomers, of the monomer, and of the polymer (PHB) are very similar (Fig. 4). Directed synthesis of the open-chain dimer and tetramer of 3-hydroxybutanoic acid and attempted cyclization do not lead to the isolation of the cyclic tetramer.
Interaction of aminomethylated resorcinarenes with rhodamine B
2009
The interaction of aminomethylated resorcinarenes with a red xanthene dye, rhodamine B, was investigated in chloroform, methanol and chloroform–methanol solutions using UV-vis, NMR and fluorescence spectroscopy. Aminomethylated resorcinarenes 1 and 2 shift the rhodamine B equilibrium from the zwitterion to the lactone form unlike reference compounds 3 and 4, which do not contain tertiary amino groups at the upper rim, giving an example of how supramolecular hosts can influence the equilibrium of rhodamine B isomers.
Synthesis of Spirovetivane Sesquiterpenes from Santonin. Synthesis of (+)-Anhydro-?-rotunol and All Diastereomers of 6,11-Spirovetivadiene.
2005
The synthesis of the spirovetivane sesquiterpenes (+)-anhydro-beta-rotunol and all the diastereomers of 6,11-spirovetivadiene in enantiomerically pure form has been achieved starting from santonin. The key step is the silicon-guided acid-promoted rearrangement of a 1-trimethylsilyl-4,5-epoxyeudesmane prepared from santonin in several steps involving lactone reductive opening, conjugate addition of TMSLi-CuCN, deoxygenation of a carbonyl group, and epoxidation. Rearrangement of the epoxide gave a spiro[4,5]decanediol which was used as a synthetic intermediate. From this compound, (+)-anhydro-beta-rotunol was prepared after elimination of the primary hydroxyl group in the side chain, followed…
Stereoselective Synthesis of (+)-11βH,13-Dihydroestafiatin, (+)-11βH,13-Dihydroludartin, (−)-Compressanolide, and (−)-11βH,13-Dihydromicheliolide fro…
2002
Starting from 2 and 3, obtained from santonin (1), we have synthesized natural guaianolides 4-7. Chemoselective epoxidation of 2 gave (+)-11betaH,13-dihydroestafiatin (4), and epoxidation of 3 followed by regioselective elimination of the hydroxyl group afforded (+)-11betaH,13-dihydroludartin (5). Sharpless' mild regioselective ring-opening of 4 and 5 followed by hydrogenolysis yielded (-)-compressanolide (6) and (-)-11betaH,13-dihydromicheliolide (7), respectively.
Qualitative and quantitative study of the mixture of two odorous compounds of wine
2003
National audience
Semisynthesis of new tetrahydrofuranic alkyl ester and furano-pyrone derivatives as inhibitors of the mitochondrial complex I
2002
Abstract Methoxymethylation of altholactone ( 1 ) led to the corresponding O -methoxymethyl derivative ( 3 ) in addition to the unexpected 6,7-dihydro-7-methoxy analogue ( 4 ), and two original tetrahydrofuranic (THF) alkyl esters ( 5 , 6 ). Moreover, when we accomplished a new method for the preparation of the furano-pyrone goniofupyrone ( 7 ) through 7-hydroxylation of 1 in acid medium, a minor compound ( 8 ) with an identical skeleton to that of compounds 5 and 6 was identified. Careful examination of the published spectral data of the reported styryl-lactones with an heptolide skeleton reveals that those structures possess also a THF alkyl ester skeleton. The revision of those structure…
Sesquiterpene lactones and lignans from Artemisia arborescens
1997
The aerial parts of Artemisia arborescens yielded, in addition to several known compounds, a new guaianolide, a new homoditerpene endoperoxide, a new lignan of the sesamin type and a new azulene derivative.