Search results for "synthesis"
showing 10 items of 2844 documents
Synthetic and Biological Applications of Fluorous Reagents as Phase Tags
2011
The search for new and better techniques for the purification of organic compounds has made the recent emergence of fluorous chemistry in the field of organic synthesis possible. Using fluorous reagents as phase tags allows for the access of different synthetic routes, and this has been translated into a time reduction and higher simplicity compared to standard, nonfluorous procedures. The synthesis in fluorous phase of target molecules can be pursued in a parallel or combinatorial manner in order to access chemical libraries with structural and/or stereochemical diversity. The preparation of radiolabeled molecules also benefits from the advantages of fluorous synthesis. Finally, biochemica…
ChemInform Abstract: Organocatalytic Enantioselective Alkylation of Pyrazol-3-ones with Isatin-Derived Ketimines: Stereocontrolled Construction of Vi…
2016
Financial support from the MINECO (Gobierno de Espana and FEDER (EU)) (CTQ2013-47949-P) and from Generalitat Valenciana (ISIC2012/001) is gratefully acknowledged. C. V. thanks MINECO for JdC contract. Access to NMR, MS and X-ray facilities from the Servei central de support a la investigacio experimental (SCSIE)-UV is also acknowledged.
Über die mikrobiologische Umwandlung N-haltiger Substrate. 3. Mitt.: Über die Konstitutionsaufklärung von Umwandlungsprodukten des 5-Hydroxyindols du…
1968
In Schuttelkulturen von Cordyceps militaris entstehen aus 5-Hydroxyindol zwei neue Substanzen, die nach Chromatographie an Polyamidsaulen und nachfolgender Isolierung auf Grund ihres chemischen Verhaltens gegenuber Diazomethan sowie ihrer Elementaranalysen, IR-, Massen-und NMR-Spektren als ω-N-Acetyl-5-hydroxy-tryptophan und ω-N-Acetyl-serotonin identifiziert wurden. Two new substances are produced in submerged cultures of Cordyceps militaris fed with 5-hydroxyindole. These substances, separated by column chromatography with polyamide and isolated afterwards, have been identified as ω-N-acetyl-5-hydroxytryptophan and ω-N-acetyl-serotonin by their reaction with diazomethane, by elementary an…
Enantioselective organocatalytic intramolecular aza-Michael reaction: a concise synthesis of (+)-sedamine., (+)-allosedamine, and (+)-coniine
2007
The intramolecular aza-Michael reaction of carbamates bearing remote alpha,beta-unsaturated aldehydes under organocatalytic conditions took place with good yields and excellent ee's when Jorgensen catalyst IV was used in the process, giving rise to the enantioselective formation of several five- and six-membered heterocycles. The developed methodology was applied to the synthesis of three piperidine alkaloids.
ChemInform Abstract: Continuous Hydrothermal Synthesis of Nanometric BaZrO3in Supercritical Water.
2008
Abstract Nanocrystalline barium zirconate (BaZrO 3 ) was synthesized using a hydrothermal synthesis process working in supercritical conditions and in a continuous way. By this method, we succeeded in the continuous and rapid production of nanopowders. As a preliminary work three barium precursors have been investigated: barium hydroxide (Ba(OH) 2 ), barium acetate (Ba(CH 3 COO) 2 ) and barium nitrate (Ba(NO 3 ) 2 ). Two of them (Ba(CH 3 COO) 2 and Ba(NO 3 ) 2 ) led to the pure perovskite phase. Then an experimental design has been conducted in order to determine the influence of the experimental parameters on the crystallinity and the grain size of the final product.
(−)-(4R,5R)-4,5-Bis[hydroxy(diphenyl)methyl]-2,2-dimethyl-1,3-dioxolane
2008
[93379-48-7] C31H30O4 (MW 466.57) InChI = 1S/C31H30O4/c1-29(2)34-27(30(32,23-15-7-3-8-16-23)24-17-9-4-10-18-24)28(35-29)31(33,25-19-11-5-12-20-25)26-21-13-6-14-22-26/h3-22,27-28,32-33H,1-2H3/t27-,28-/m1/s1 InChIKey = OWVIRVJQDVCGQX-VSGBNLITSA-N (chiral shift reagent; chiral host in inclusion compounds; chiral reagent; chiral ligand for asymmetric catalysis) Alternate Name: TADDOL. Physical Data: mp: 190–192 °C1a; 195–196.5 °C1b; 192–193 °C;1c,e 193.5–195 °C;1d [α]RTd=−68.5 °(c = 1, CH3Cl);1a [α]d = −60.6 °(c = 1, CH3Cl);1b [α]20d = −67 ° (c = 1, CH3Cl);1c [α]20d = −65.1° (c = 1, CH3Cl);1d [α]20d = −64.6°(c = 1, CH3Cl)1e Solubility: soluble in toluene, cyclohexane, dichloromethane and tetra…
Bleomycin, an Antibiotic That Removes Thymine from Double-Stranded DNA
1977
Publisher Summary This chapter reviews that bleomycins are members of a new class of DNA-modifying agents, the quasi-enzymes. In in vitro systems, bleomycin first removes thymines from native DNA by hydrolysis of the N-glycosidic bonds without modifying the deoxyribose moiety. In a second step, single-strand scissions occur at the sites of the nonglycosidic deoxyribose moieties, resulting in the formation of 3'-OH and 5'-P termini. It is suggested that bleomycin is bound to DNA by interaction of the positively charged terminal amine moiety with the negatively charged phosphate group in DNA; intercalation seems to be involved in binding. Bleomycin is inactivated by copper and zinc ions, prob…
Cyclocondensation of alpha-aminonitriles and enones: a short access to 3,4-dihydro-2H-pyrrole 2-carbonitriles and 2,3,5-trisubstituted pyrroles.
2009
The reaction of alpha,beta-unsaturated carbonyl compounds with aminoacetonitrile hydrochloride furnishes 3,5-disubstituted 3,4-dihydro-2H-pyrrole-2-carbonitriles in a one-pot reaction sequence. While these products can serve as starting materials for the preparation of polysubstituted pyrrolizidines, they are kinetically stable against the base-induced elimination of HCN. In contrast, their 2-substituted analogues obtained from alpha-substituted alpha-aminonitriles can be readily converted to the corresponding 2,3,5-trisubstituted pyrroles under microwave irradiation. The key step presumably involves the thermal electrocyclization of a stabilized 2-azapentadienyl anion formed by condensatio…
Microwave-Assisted Synthesis of Polysubstituted 4-Quinolones from Deprotonated α-Aminonitriles
2010
The α-alkylation of deprotonated N-aryl-α-aminonitriles with α-bromoesters furnishes intermediates that can be cyclized to 4-quinolones upon microwave irradiation. Alternatively, base-induced dehydrocyanation of the alkylation products furnishes enaminoesters, which can, for example, be converted into quinoline-3-carboxylates.
One-Pot Synthesis of (±)-Crispine A and Its C-Ring-Substituted Analogs
2006
A straightforward access to crispine A and C-ring-substituted analogs by 1,4-addition of a deprotonated α-amino nitrile to α,β-unsaturated carbonyl compounds is described. If the reduction step is omitted, substituted 5,6-dihydropyrrolo[2,1-a]isoquinolines can be obtained. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)