نتایج جستجو برای: multisubstituted pyrroles

تعداد نتایج: 2001  

Journal: :Canadian Journal of Chemistry 1972

Journal: :Acta Chemica Scandinavica 1952

Journal: :Organic & biomolecular chemistry 2015
Shuai-Shuai Li Hui Lin Xiao-Mei Zhang Lin Dong

In this paper, a simple and highly efficient ruthenium-catalyzed direct C3 alkylation of indoles with various α,β-unsaturated ketones without chelation assistance has been developed. This novel C-H activation methodology exhibits a broad substrate scope such as different substituted indoles, pyrroles, and other azoles. Further synthetic applications of the alkylation products can lead to more a...

Journal: :Organic & biomolecular chemistry 2015
Ganesan Bharathiraja Mani Sengoden Masanam Kannan Tharmalingam Punniyamurthy

Various tetrasubstituted pyrroles/pyrazoles have been prepared from nitro-substituted 1,3-enynes with aromatic amines/hydrazines via a copper-catalyzed cascade aza-Michael addition, cyclization and aromatization at room temperature. This protocol is also effective for the synthesis of tetrasubstituted pyrazoles in high yields.

Journal: :Chemical communications 2010
Srinath Thirumalairajan Beth M Pearce Alison Thompson

This review summarizes strategies by which chiral pyrroles, both simple and complex, have been prepared: strategies include formation of the pyrrolic ring using starting materials appended with chirality, as well as the attachment of chirality to a pre-formed pyrrolic ring.

Journal: :Chemical communications 2015
Sridhar Undeela Srinivas Thadkapally Jagadeesh Babu Nanubolu Kiran Kumar Singarapu Rajeev S Menon

Gold-catalysed, divergent synthesis of 2-sulfonylmethyl pyrroles and dihydropyridines from N-propargyl-N-vinyl sulfonamides has been achieved. Echavarren's gold(I) catalyst promoted the formation of pyrrole derivatives whereas the combination of PPh3AuCl and AgSbF6 afforded dihydropyridines. The aza-enyne precursors for the cycloisomerisation reaction were prepared by a base-mediated formal vin...

Journal: :Chemical communications 2014
Yamuna Ariyarathna Jon A Tunge

The reaction of Meldrum's acid, pyrrolide, and allyl carbonates allows a multicomponent decarboxylative coupling to form allylated acyl pyrroles. This strategy is made possible by the in situ formation of β-oxo carboxylates from Meldrum's acid. Subsequent decarboxylative enolate formation and electrophilic allylation complete the reaction. Addition of benzylidene malononitriles as good Michael ...

Journal: :Organic & biomolecular chemistry 2015
Ana B Cuenca Jessica Cid Diego García-López Jorge J Carbó Elena Fernández

We have experimentally proved the unsymmetrical 1,1-diboration of diazo compounds, formed in situ from aldehydes and cyclic and non-cyclic ketones, in the absence of any transition metal complex. The heterolytic cleavage of the mixed diboron reagent, Bpin-Bdan, and the formation of two geminal C-Bpin and C-Bdan bonds has been rationalised based on DFT calculations to occur via a concerted-async...

Journal: :The Journal of organic chemistry 2006
Daniela Andrei Stanislaw F Wnuk

[reaction: see text] The 1-fluoro-1-haloalkenes undergo Pd-catalyzed Negishi cross-couplings with primary alkylzinc bromides to give multisubstituted fluoroalkenes. The alkylation was trans-selective giving pure Z-fluoroalkenes in most cases. The highest yields were obtained with Pd2(dba)3 and PdCl2(dppb) catalysts but the best stereochemical outcome was obtained with less reactive Pd(PPh3)4. T...

Journal: :Chemical communications 2015
Dipak Kumar Tiwari Jaya Pogula B Sridhar Dharmendra Kumar Tiwari Pravin R Likhar

Nano-copper(0) stabilized on alumina prepared from Cu-Al hydrotalcite has been reported for completely regioselective synthesis of 2,4-disubstituted pyrroles from unactivated terminal aromatic/aliphatic alkynes and isocyanides. The reaction is operationally simple, involves ligand-free inexpensive nano-copper, and affords products in high yields.

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