نتایج جستجو برای: 1 3 dipolar cycloaddition
تعداد نتایج: 3600098 فیلتر نتایج به سال:
The catalytic highly regio-, diastereo-, and enantioselective synthesis of a small library of spiropyrrolizidineoxindolesvia a four-component 1,3-dipolar cycloaddition reactionof azomethineylides, derived from isatin, with electron-deficient dipolarophilewas described. The process occurs at room temperature in aqueous ethanol as a green solvent and in the presence of a bidendatebis(imi...
Synthesis of enantiomerically pure isoxazolidine via an asymmetric 1,3- dipolar cycloaddition reaction of nitrone with electron-deficient dipolarophile was described. The process occurs at room temperature in aqueous ethanol as a green solvent and in the presence of a bidendate bis(imine)–Cu(II)triflate complex as catalyst. The reaction mechanism is discussed on the basis of the assignment of t...
The catalytic highly regio-, diastereo-, and enantioselective synthesis of a small library of spiropyrrolizidineoxindolesvia a four-component 1,3-dipolar cycloaddition reactionof azomethineylides, derived from isatin, with electron-deficient dipolarophilewas described. The process occurs at room temperature in aqueous ethanol as a green solvent and in the presence of a bidendatebis(imi...
A novel one-pot two step tandem reaction for the synthesis of indolizine-1-carbonitrile derivatives (5a-i) was identified. The route comprises 1,3-dipolar cycloaddition reaction of aromatic aldehyde derivatives (1a-i), malononitrile (2) and 1-(2-(4-bromophenyl)-2-oxoethyl)-2-chloropyridin-1-ium (4) under ultrasound irradiation at room temperature in the presence of triethylamine at acetonitrile...
A series of carbapenems containing novel C-2 semisaturated heterocyclic substituents were synthesised by 1,3 dipolar cycloaddition reactions of nitrile oxides, nitrile imines and a nitrone to 2-vinylcarbapenem. The isoxazoline and isoxazolidine compounds showed potent antibacterial activity but moderate stability to human dehydropeptidase 1 (DHP-1). Stability to DHP-1 was improved by methyl sub...
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Abstract This short review describes the assistance of click chemistry in chemical modification glycosaminoglycans. Through an alkyne-azide 1,3-dipolar cycloaddition reaction, chemically and physiologically stable triazole unit connects glycosaminoglycans with other labelled or attached functionalities. The synthesized glycosaminoglycan (GAG) conjugates act as drug carriers, forming hydrogels n...
The diversely functionalized tricyclic tetrazoles were synthesised from readily available substrates via intramolecular 1,3-dipolar cycloaddition as the key step in good yields (53-78% yield for two steps) with high enantioselectivities (81-99% ee).
Five-fold symmetric substituted corannulene derivatives that display liquid-crystalline behavior and organogelation properties were prepared by coupling of N-azidoethyl long-chain fatty acid amides to sym-pentabutynyl corannulenes via dipolar cycloaddition chemistry.
Condensation of an aldehyde with an α-amino-ester, followed by a tandem process involving cyclization to a seven-membered ring, deprotonation to an intermediate azomethine ylide and intramolecular dipolar cycloaddition gave tricyclic products related to stenine and neostenine.
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