@article { ISI:000317327900086, title = {NHC-Catalyzed reaction of enals with hydroxy chalcones: diastereoselective synthesis of functionalized coumarins}, journal = {Organic Letters}, volume = {15}, number = {7}, year = {2013}, month = {APR}, pages = {1756-1759}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The N-heterocyclic carbene-catalyzed annulation of enals with 2{\textquoteright}-hydroxy chalcones afford cyclopentane-fused coumarin derivatives with an excellent level of diastereocontrol. The reaction tolerates a broad range of functional groups; 25 examples are given, and a preliminary mechanistic investigation is provided.

}, issn = {1523-7060}, doi = {10.1021/ol400562z}, author = {Bhunia, Anup and Patra, Atanu and Puranik, Vedavati G. and Biju, Akkattu T.} } @article { ISI:000344459400014, title = {N-Heterocyclic carbene-catalyzed enantioselective synthesis of functionalized cyclopentenes via alpha,beta-unsaturated acyl azoliums}, journal = {Chemical Communications}, volume = {50}, number = {93}, year = {2014}, month = {OCT}, pages = {14539-14542}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Highly enantioselective NHC-organocatalyzed synthesis of functionalized cyclopentenes proceeding via alpha,beta-unsaturated acyl azolium intermediates is reported. The organocascade reaction of modified enals with malonic ester derivatives having a gamma-benzoyl group involves the Michael-intramolecular aldol-beta-lactonization-decarboxylation sequence to deliver cyclopentenes in good yields and excellent ee values.

}, issn = {1359-7345}, doi = {10.1039/c4cc07433e}, author = {Mondal, Santigopal and Yetra, Santhivardhana Reddy and Patra, Atanu and Kunte, Sunita S. and Gonnade, Rajesh G. and Biju, Akkattu T.} } @article {42434, title = {N-Heterocyclic carbene-catalyzed diastereoselective synthesis of β-lactone-fused cyclopentanes using homoenolate annulation reaction}, journal = {Chemical Communications}, volume = {51}, year = {2015}, month = {MAY}, pages = {9559-9562}, abstract = {

NHC-catalyzed annulation of enals with 2-enoylpyridines or 2-enoylpyridine\ N-oxides leading to the diastereoselective synthesis of β-lactone-fused cyclopentanes is reported. The reaction proceeds\ via\ the generation of homoenolate equivalent intermediates and tolerates a broad range of functional groups.

}, doi = {10.1039/C5CC02960K}, author = {Mukherjee, Subrata and Mondal, Santigopal and Patra, Atanu and Gonnade, Rajesh G. and Biju, Akkattu T.} } @article {43352, title = {N - heterocyclic - carbene - catalyzed umpolung of imines}, journal = {Angewandte Chemie International Edition}, volume = {56}, year = {2017}, month = {MAR}, pages = {2730 - 2734}, type = {Article}, abstract = {

N-Heterocyclic carbene (NHC) catalysis has been widely used for the umpolung of aldehydes, and recently for the umpolung of Michael acceptors. Described herein is the umpolung of aldimines catalyzed by NHCs, and the reaction likely proceeds via aza-Breslow intermediates. The NHC-catalyzed intramolecular cyclization of aldimines bearing a Michael acceptor resulted in the formation of biologically important 2-(hetero)aryl indole 3-acetic-acid derivatives in moderate to good yields. The carbene generated from the bicyclic triazolium salt was found to be efficient for this transformation.

}, doi = {10.1002/anie.201611268}, author = {Patra, Atanu and Mukherjee, Subrata and Das, Tamal Kanti and Jain, Shailja and Gonnade, Rajesh Ghanshyam and Biju, Akkattu T.} } @article {44621, title = {N-Heterocyclic carbene-catalyzed synthesis of alpha-trifluoromethyl esters}, journal = {Organic Letters}, volume = {20}, year = {2018}, month = {JUL}, pages = {3897-3901}, abstract = {

The N-heterocyclic carbene (NHC)-catalyzed trifluoromethylation of alpha-chloro aldehydes was developed, allowing straightforward access to valuable alpha-trifluoromethyl ester derivatives. The unique combination of an electrophilic trifluoromethylation reagent with NHC catalysis was the key for the functionalization of a broad range of alpha-chloro aldehydes, and the products are formed in moderate to good yields. Investigations of the enantioselective version of this reaction afforded the enantioenriched products in moderate yields with good ee values.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.8b01482}, author = {Gelat, Fabien and Patra, Atanu and Pannecoucke, Xavier and Biju, Akkattu T. and Poisson, Thomas and Besset, Tatiana} }