@article { ISI:000295113200015, title = {Asymmetric dihydroxylation route to (-)-bulgecinine}, journal = {Tetrahedron-Asymmetry}, volume = {22}, number = {11}, year = {2011}, month = {JUN}, pages = {1234-1238}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

The stereoselective synthesis of (-)-bulgecinine is reported from L-aspartic acid using Sharpless asymmetric dihydroxylation and intramolecular cyclization via nucleophilic displacement of alpha-tosylate as key steps. (C) 2011 Elsevier Ltd. All rights reserved.

}, issn = {0957-4166}, doi = {10.1016/j.tetasy.2011.06.018}, author = {Show, Krishanu and Upadhyay, Puspesh K. and Kumar, Pradeep} } @article { ISI:000295113200011, title = {Stereoselective synthesis of ophiocerins A and C}, journal = {Tetrahedron-Asymmetry}, volume = {22}, number = {11}, year = {2011}, month = {JUN}, pages = {1212-1217}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

An efficient synthesis of ophiocerins A and C has been achieved via a common intermediate. The stereogenic centers were generated by means of Jacobsen{\textquoteright}s hydrolytic kinetic resolution and Sharpless kinetic resolution. (C) 2011 Elsevier Ltd. All rights reserved.

}, issn = {0957-4166}, doi = {10.1016/j.tetasy.2011.06.015}, author = {Show, Krishanu and Gupta, Priti and Kumar, Pradeep} } @article { ISI:000324460900018, title = {Concise synthesis of (5R,6S)-tert-butyl 5-acetoxy-6-(hydroxymethyl)-5,6-dihydropyridine-1(2H)-carboxylate}, journal = {Arkivoc}, number = {2}, year = {2013}, month = {OCT}, pages = {220-227}, publisher = {ARKAT USA INC}, address = {C/O ALAN R KATRITZKY, UNIV FLORIDA, DEPT CHEMISTRY, PO BOX 117200, GAINESVILLE, FL 32611 USA}, abstract = {

An efficient synthesis of (5R,6S)-tert-butyl 5-acetoxy-6-(hydroxymethyl)-5,6-dihydropyridine-1(2H)-carboxylate 1, a common intermediate for various polyhydroxylated piperidines is reported in six steps with 32\% overall yield starting from Garner{\textquoteright}s aldehyde. The key steps include the diastereoselective nucleophilic addition and intramolecular cyclization. (5R,6S)-tert-butyl 5-acetoxy-6-(hydroxymethyl)-5,6-dihydropyridine-1(2H)-carboxylate is a common precursor for the synthesis of 1-deoxy-L-mannojirimycin, 1-deoxy-L-idonojirimycin, L-fagomycin and related analogues.

}, keywords = {cyclization, Garner{\textquoteright}s aldehyde, nucleophilic addition, polyhydroxy piperidines}, issn = {1551-7004}, author = {Ramalingam, S. and Bhise, Ankushkumar D. and Show, Krishanu and Kumar, Pradeep} } @article { ISI:000347602400004, title = {Chemoselective deprotection of N-allylic amines using DDQ}, journal = {Tetrahedron Letters}, volume = {55}, number = {52}, year = {2014}, month = {DEC}, pages = {7172-7176}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

A highly chemoselective and simple method for the deprotection of N-allylic amines using DDQ has been developed. The use of DDQ in dichloromethane-water provides a mild and efficient one-step deallylation of a wide variety of orthogonally protected tertiary amine derivatives. (C) 2014 Elsevier Ltd. All rights reserved.

}, keywords = {Chemoselective deprotection, DDQ, N-Allylic amines, Orthogonally protected tertiary amines}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2014.10.136}, author = {Kumar, Pradeep and Cherian, Shijo K. and Jain, Ruchi and Show, Krishanu} } @article {43372, title = {Synthesis of ophiocerins A, B and C, botryolide E, decarestrictine O, stagonolide C and 9-epi-stagonolide C employing chiral hexane-1,2,3,5-tetraol derivatives as building blocks}, journal = {European Journal of Organic Chemistry}, volume = {27}, year = {2016}, month = {SEP}, pages = {4696-4710}, abstract = {An organocatalytic approach to the synthesis of (2R,3S)-hexane-1,2,3,5-tetraol (11) derivatives (in the forms of different stereoisomers and bearing different protecting groups) has been developed. The key chiral intermediates 11 were prepared with complete stereocontrol through the proline-catalyzed intermolecular aldol reaction between acetone and d-glyceraldehyde acetonide. The synthetic utility of the intermediates was demonstrated by their transformation into the title hydroxylated pyrans and a variety of unsaturated lactones through standard synthetic protocols.}, doi = {10.1002/ejoc.201600625}, author = {Show, Krishanu and Kumar, Pradeep} } @article {44654, title = {First total synthesis of the proposed structure of pandangolide 1}, journal = {European Journal of Organic Chemistry}, year = {2018}, month = {JUL}, pages = {3352-3364}, abstract = {

The first total synthesis of the proposed structure of pandangolide 1 is reported. The synthesis was carried out using both an organocatalytic approach and a chiral-pool approach. The required stereochemistry at C-3 and C-5 was installed by using an organocatalytic aldol reaction and a stereoselective ketone reduction. The construction of the 12-membered core was achieved by 2-methyl-6-nitrobenzoic anhydride-mediated Shiina lactonization. The structure of target molecule was confirmed unambiguously by single-crystal X-ray analysis, but the optical rotation and NMR spectroscopic data of the synthetic pandangolide 1 were found to be inconsistent with the natural product.

}, keywords = {lactones, Macrocycles, Natural products, structure elucidation, synthesis design, Total synthesis}, issn = {1434-193X}, doi = {10.1002/ejoc.201800675}, author = {Show, Krishanu and Gonnade, Rajesh G. and Kumar, Pradeep} }