Search results for "Bicyclic molecule"
showing 10 items of 254 documents
Reactions of 1-isopropyl-3-methyl- and 2,3-dimethylindoles with triethyl orthoformate: New trisindolylmethanes
1987
Indoles 1 and 2 react with triethyl orthoformate under proton–catalyzed conditions to form trisindolylmethanes. The regioisomer distribution of the products is controlled by steric and electronic factors.
Triazolopyridines. 14. Substitution reactions of 7-amino[1,2,3]triazolo[1,5-a]pyridines.
1993
Abstract Reaction between 7-aminotriazolopyridines 1 or 2 and sulphuric acid gives hydroxyalkylpyridines 3 and 4 ; bromination gives brominated pyridine 5 or triazolopyridine 6. The anions from amines 1 or 2 are ambident, acylating on N but alkylating on N or on C6; in the latter case triazolylalkenylcyanides 16 – 20 or the 6,6-dialkylated derivative 19 are obtained. An X-ray diffraction study has confirmed structure 19.
Exploring reactivity of a bis-sulfonium zirconocene-ate dimer: synthesis of various zwitterionic phosphonium anionic zirconocene complexes
2007
Abstract Formal [3+2] cycloaddition reactions between the bis-sulfonium zirconocene-ate dimer 1a and methylpropiolate, benzaldehyde and carbon disulfide afforded stable zwitterionic phosphonium zirconocene-ate complexes 2–4, respectively, with two orthocondensed five-membered heterocycles. X-ray crystal structure of 4 has been determined. Elemental chalcogens (S, Se, Te) gave rise also to a new variety of five-coordinate zirconium(IV) complexes (5–7) by a formal [3+1] cycloaddition reaction. In these bicyclic zirconates, sulfur is included in a five-membered ring while the second chalcogen is in a four-membered one.
Synthesis of a new family of bi- and polycyclic compounds via Pd-catalyzed amination of 1,7-di(3-bromobenzyl)cyclen
2008
Abstract New bicyclic cryptand type compounds are synthesized by reacting 1,7-di(3-bromobenzyl)cyclen with 1 equiv of linear polyamines under dilute conditions using Pd-catalyzed amination. Bis(cyclen) and tris(cyclen) compounds containing linear polyamine linkers between benzylated cyclens are obtained by a similar procedure using different reaction conditions. Cyclization of these species via intramolecular catalytic diamination led to tri- and tetracyclic polyaza compounds.
Antimykotische Wirkstoffe, Mitt. Chlor-(1-piperazinyl)-1,3,5-triazine
1988
Aus der Umsetzung von Cyanurchlorid (1) mit den Piperazinderivaten 2a–c bei –20 bis 10° gehen die Dichlor-(1-piperazinyl)-1,3,5-triazine 3a–c hervor. Bei der erhohten Reaktionstemperatur von 40° erfolgt aus 1 und den Piperazinderivaten 4a–b Bildung der 2-Chlor-4,6-bis(piperazinyl)-1,3,5-triazine 5a–b. Zu gemischt substituierten Chlor-1,3,5-triazinen 9 fuhrt die nacheinander erfolgende Umsetzung von 1 mit 2 verschiedenen cyclischen sekundaren Aminen (6 und 8). Die Strukturtypen 3, 5 und 9 zeigen in den 1H-NMR-Spektren zwei fur Piperazinringe charakteristische Signalgruppen im Bereich 2.4–4.0 ppm. Unter den neu entwickelten Verbindungen finden sich Vertreter mit sehr starker antimykotischer W…
New umbelliferone sesquiterpene ethers from roots ofLigularia persica
1991
An extract of roots of Ligularia persica yielded thirteen umbelliferone sesquiterpene ethers, among them the new ones ligupersin A (11) and ligupersin B (13).
Synthesis of conformationally restricted 1,2,3-triazole-substituted ethyl β- and γ-aminocyclopentanecarboxylate stereoisomers. Multifunctionalized al…
2010
Abstract Stereoisomers of 1,2,3-triazole-functionalized, conformationally restricted β- or γ-amino esters with a cyclopentane skeleton were efficiently synthetized from the bicyclic β-lactam 6-azabicyclo[3.2.0]hept-3-en-7-one (1) and Vince γ-lactam (15) in five or six steps involving the azide–alkyne 1,3-dipolar cycloaddition of azido-substituted amino ester stereoisomers with nonsymmetric acetylenes. The azide–alkyne click reactions were investigated under thermal and Cu(I)-catalyzed conditions. Surprisingly, the thermally induced cycloaddition furnished the corresponding 1,4-triazoles regioselectively, which also took place selectively in response to Cu(I) catalysis.
Stereoselective Conjugate Addition of Mixed Organoaluminum Reagents to ?,?-Unsaturated N-Acyloxazolidinones Derived from Carbohydrates.
2005
The stereoselective synthesis of β-branched carboxylic acid derivatives was accomplished by conjugate addition of mixed organoaluminum reagents to chiral α,β-unsaturated N-acyloxazolidinones. Mixed organoaluminum reagentswere generated in situ by transmetalation of Grignard or organolithium compounds with methylaluminum dichloride. Efficient stereocontrol was achieved using different bicyclic glycosamine-derived oxazolidinones, yielding alternatively (R)- or (S)-configured β-branched carboxylic acid derivatives.
Stereoselective Synthesis of the Glycosidase Inhibitor Australine through a One-Pot, Double-Cyclization Strategy
2006
[reaction: see text] A stereocontrolled, convergent synthesis of the alkaloid australine, a glycosidase inhibitor of the pyrrolizidine class, is described. The chiral starting materials were ketone 3, derived from L-erythrulose, and alpha-alkoxy aldehyde 4, prepared from L-malic acid. A key step of the synthesis was the highly stereoselective aldol reaction between 4 and a Z boron enolate derived from 3. Another key step was the one-pot construction of the bicyclic pyrrolizidine system by means of a three-step sequence of SN2 displacements induced by benzylamine on a trimesylate precursor.
ChemInform Abstract: Diastereoselective Intramolecular Additions of Allyl- and Propargylsilanes to Iminium Ions: Synthesis of Cyclic and Bicyclic Qua…
2010
Cyclization of the chiral imino lactones with allylic or propargylic groups required acidic conditions to afford spirocyclic (II) or (XII).