@article { ISI:000253620600008, title = {Use of the pictet-spengler reaction for the synthesis of 1,4-disubstituted-1,2,3,4-tetrahydro-beta-carbolines and 1,4-disubstituted-beta-carbolines: formation of gamma-carbolines}, journal = {Tetrahedron}, volume = {64}, number = {8}, year = {2008}, month = {FEB}, pages = {1654-1662}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Microwave-assisted conjugate addition of indole on nitro-olefins furnished nitro compounds, which were reduced to tryptamines. Further, by using Pictet-Spengler condensation, new 1,4-disubstituted-1,2,3,4-tetrahydro-beta-carbolines were synthesized in diastereoselective manner. Dehydrogenation of the tetrahydro-beta-carbolines produced new 1,4-disubstituted-beta-carbolines. As a new observation, in some of the cases, Pictet-Spengler condensation and dehydrogenation gave two products, namely 1,4-disubstituted-beta-carbolines and 1,4-disubstituted-gamma-carbolines. A mechanism is proposed for this observation. (C) 2007 Elsevier Ltd. All rights reserved.

}, keywords = {1, 2, 3, 4-Disubstituted-1, 4-disubstituted-beta-carboline, 4-disubstituted-gamma-carboline, 4-tetrahydro-beta-carboline, 4-tetrahydro-gamma-carboline, Pictet-Spengler reaction}, issn = {0040-4020}, doi = {10.1016/j.tet.2007.12.008}, author = {Kusurkar, Radhika S. and Alkobati, Nabil A. H. and Gokule, Anita S. and Puranik, Vedavati G.} } @article { ISI:000290685100004, title = {Diastereoselective synthesis of 1,1,4-trisubstituted-2,3,4,9-tetrahydrospiro-beta-carbolines via glacial acetic acid catalyzed pictet - spengler reaction}, journal = {Arkivoc}, number = {2}, year = {2011}, month = {OCT}, pages = {41-56}, publisher = {ARKAT USA INC}, address = {C/O ALAN R KATRITZKY, UNIV FLORIDA, DEPT CHEMISTRY, PO BOX 117200, GAINESVILLE, FL 32611 USA}, abstract = {

The Pictet-Spengler reaction of substituted tryptamines with cyclic ketones using glacial acetic acid afforded only one diastereomer of unreported 1,1,4-trisubstituted-2,3,4,9-tetrahydrospiro-beta-carbolines. The stereoselectivity in the reaction has been demonstrated using unsymmetrical ketones and single-crystal X-ray analysis of one of the spiro products in the form of base, its sulfate and hydrochloride salts, which indicated the formation of only the R, R diastereomer.

}, keywords = {1, 3, 4, 4-Trisubstituted-2, 9-tetrahydrospiro-beta-carbolines, beta-substituted tryptamine, Diastereoselective Pictet-Spengler reaction, Glacial acetic acid}, issn = {1551-7004}, author = {Shumaila, Abdullah M. A. and Puranik, Vedavati G. and Kusurkar, Radhika S.} } @article { ISI:000290602100011, title = {Diastereoselective synthesis of tetrasubstituted-octahydro-3,6-diazacarbazoles and tetrasubstituted-3,6-diazacarbazoles via double Pictet-Spengler reaction}, journal = {Tetrahedron Letters}, volume = {52}, number = {21}, year = {2011}, month = {MAY}, pages = {2661-2663}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Pictet-Spengler condensation of 2,5-bis(2-phenyl-1-aminoethyl)pyrrole using glacial acetic acid afforded only one diastereomer of unreported tetrasubstituted-octahydro-3,6-diazacarbazoles. These were readily dehydrogenated to tetrasubstituted-3,6-diazacarbazoles. The stereoselectivity in the Pictet-Spengler reaction has been demonstrated using single crystal X-ray analysis. (C) 2011 Elsevier Ltd. All rights reserved.

}, keywords = {2, 5-Bis(2-phenyl-1-aminoethyl)pyrrole, 6-diazacarbazoles, Diasteroselective Pictet-Spengler reaction, Glacial acetic acid, Tetrasubstituted-3, Tetrasubstituted-octahydro-3}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2011.03.060}, author = {Shumaila, Abdullah M. A. and Puranik, Vedavati G. and Kusurkar, Radhika S.} } @article { ISI:000286995800020, title = {Synthesis of tetrahydro-5-azaindoles and 5-azaindoles using pictet-spengler reaction-appreciable difference in products using different acid catalysts}, journal = {Tetrahedron}, volume = {67}, number = {5}, year = {2011}, month = {FEB}, pages = {936-942}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Pictet-Spengler condensation of 2-(aryl)-2-(1H-pyrrol-2-yl)ethanamines using conventional acid catalysts like TMSCl or TFA resulted in the formation of substituted 5-azaindoles involving a tandem one pot four steps reaction sequence. By contrast use of glacial acetic acid furnished the targeted tetrahydro-5-azaindoles in diastereoselective manner. These were readily dehydrogenated to 5-azaindoles. (C) 2010 Elsevier Ltd. All rights reserved.

}, keywords = {2-(Aryl)-2-(1H-pyrrol-2-yl)ethanamines, 4, 7-Disubstituted-5-azaindoles, 7-Disubstituted-tetrahydro-5-azaindoles, Diastereoselective Pictet-Spengler reaction}, issn = {0040-4020}, doi = {10.1016/j.tet.2010.12.003}, author = {Shumaila, Abdullah M. A. and Puranik, Vedavati G. and Kusurkar, Radhika S.} } @article { ISI:000304387800025, title = {Efficient total synthesis of calothrixin B}, journal = {Tetrahedron Letters}, volume = {53}, number = {23}, year = {2012}, month = {JUN}, pages = {2894-2896}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

An efficient synthesis of calothrixin B (2) is demonstrated starting from 9H-carbazol-4-ol, having two one-pot reaction sequences as key steps. As a novel observation, DMF-methanol was shown to be a hydride donor for reduction of aldehyde to alcohol. Unexpectedly, nucleophilic substitution of benzyloxy by methoxy group was observed. (C) 2012 Elsevier Ltd. All rights reserved.

}, keywords = {Calothrixin B, CAN, DMF-methanol, Hydride donor}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2012.03.131}, author = {Bhosale, Shrikar M. and Gawade, Rupesh L. and Puranik, Vedavati G. and Kusurkar, Radhika S.} } @article { ISI:000308628900033, title = {New synthetic route for 1,2-diketo compounds using unexpected C-C bond cleavage by PCC}, journal = {Tetrahedron Letters}, volume = {53}, number = {39}, year = {2012}, month = {SEP}, pages = {5327-5330}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

An efficient method has been established for the preparation of 1,2-diketones by unexpected C-C bond cleavage in 4-keto-2-hydroxy esters using pyridiniumchlorochromate (PCC). (c) 2012 Elsevier Ltd. All rights reserved.

}, keywords = {1, 2-Diketones, C-C bond cleavage, PCC}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2012.07.095}, author = {Bhosale, Shrikar M. and Momin, Aadil A. and Gawade, Rupesh L. and Puranik, Vedavati G. and Kusurkar, Radhika S.} } @article { ISI:000302540600008, title = {Regio- and stereoselective synthesis of new substituted tetrahydrocarbazoles and carbazoles using diels-alder reactions}, journal = {Synthetic Communications}, volume = {42}, number = {12}, year = {2012}, month = {NOV}, pages = {1786-1795}, publisher = {TAYLOR \& FRANCIS INC}, type = {Article}, address = {325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA}, abstract = {

Diels-Alder reactions of 3-vinylindoles were carried out with methyl acrylate and N-phenylmaleimide as dienophiles under microwave conditions to furnish unreported tetrahydrocarbazoles regio- and stereoselectively in good yields. Further dehydrogenation resulted in new substituted carbazoles.

}, keywords = {Carbazoles, regio- and stereoselective Diels-Alder reactions, tetrahydrocarbazoles}, issn = {0039-7911}, doi = {10.1080/00397911.2010.544440}, author = {Hingane, Dattatray G. and Goswami, Shailesh K. and Puranik, Vedavati G. and Kusurkar, Radhika S.} } @article { ISI:000329960500033, title = {Unexpected observations during the total synthesis of calothrixin B-sodium methoxide as a source of hydride}, journal = {Tetrahedron Letters}, volume = {55}, number = {1}, year = {2014}, month = {JAN}, pages = {155-162}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

During the total synthesis of calothrixin B, various novel and unexpected results were noticed such as cleavage of C-N bond in imine using sodium cyanoborohydride, sodium methoxide as a hydride source for reduction, deformylation in the presence of bromine, and deacylation using ceric ammonium nitrate (CAN). A detailed mechanism has been proposed for the unexpected results and a few of them are generalized. Temperature dependent NMR studies have been carried out for confirmation of the structure of one of the intermediates in the synthetic sequence. (C) 2013 Elsevier Ltd. All rights reserved.

}, keywords = {Azoxybenzene, Calothrixin B, reduction, Sodium cyanoborohydride, Sodium methoxide}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2013.10.140}, author = {Bhosale, Shrikar M. and Momin, Aadil A. and Kunjir, Shrikant and Rajamohanan, P. R. and Kusurkar, Radhika S.} }