@article { ISI:000226332600017, title = {Efficient stereoselective synthesis of (2S,4S,5R)-(-)- and (2R,4R,5S)-(+)-bulgecinine}, journal = {Tetrahedron Letters}, volume = {46}, number = {3}, year = {2005}, month = {JAN}, pages = {439-441}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

A short synthetic route to (-)-and (+)-bulgecinine, the amino acid moiety of the bulgecins was achieved from the readily available nonchiral pool starting material cis-2-butene-1,4-diol in which a Claisen orthoester rearrangement and a Sharpless asymmetric dihydroxylation were used as the key steps. (C) 2004 Elsevier Ltd. All rights reserved.

}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2004.11.101}, author = {Chavan, Subhash P. and Praveen, C. and Sharma, P. and Kalkote, Uttam R.} } @article { ISI:000252219700011, title = {Efficient and practical total synthesis of (+/-)-alpha-cuparenone}, journal = {Synthesis-Stuttgart }, number = {24}, year = {2007}, month = {DEC}, pages = {3827-3830}, publisher = {GEORG THIEME VERLAG KG}, type = {Article}, address = {RUDIGERSTR 14, D-70469 STUTTGART, GERMANY}, abstract = {

A one-pot cyclopentannulation approach as the key step for the total synthesis of (+/-)-alpha-cuparenone is described.

}, keywords = {Alkylation, annulation, hydroboration-oxidation, reduction}, issn = {0039-7881}, doi = {10.1055/s-2007-990899}, author = {Chavan, Subhash P. and Dhawane, Abasaheb N. and Kalkote, Uttam R.} } @article { ISI:000278985800034, title = {Enantioselective synthesis of (R)-(+)-alpha-lipoic acid via proline-catalyzed sequential alpha-aminoxylation and HWE olefination of aldehyde}, journal = {Tetrahedron Letters}, volume = {51}, number = {27}, year = {2010}, month = {JUL}, pages = {3587-3589}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

An efficient enantioselective synthesis of (R)-(+)-alpha-lipoic acid is described, in high optical purity (\>97\% ee), using L-proline-catalyzed sequential alpha-aminoxylation and Horner-Wadsworth-Emmons olefination of aldehyde as the key step. (C) 2010 Elsevier Ltd. All rights reserved.

}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2010.05.007}, author = {Panchgalle, Sharad P. and Jogdand, Ganesh F. and Chavan, Subhash P. and Kalkote, Uttam R.} } @article { ISI:000290409100007, title = {Exploration of L-proline-catalyzed -aminoxylation of aldehyde to (S)-guaifenesin-related drug molecules}, journal = {Synthetic Communications}, volume = {41}, number = {13}, year = {2011}, month = {MAY}, pages = {PII 937137930}, publisher = {TAYLOR \& FRANCIS INC}, address = {325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA}, abstract = {

[image omitted] An efficient enantioselective synthesis of (S)-guaifenesin with 99\% ee using L-proline-catalyzed -aminoxylation of aldehyde as key step is described and explored for asymmetric syntheses of (S)-moprolol and (R)-methocarbamol.

}, keywords = {-Aminoxylation, guaifenesin, methocarbamol, moprolol, Proline}, issn = {0039-7911}, doi = {10.1080/00397911.2010.493631}, author = {Panchgalle, Sharad P. and Kunte, Sunita S. and Chavan, Subhash P. and Kalkote, Uttam R.} } @article { ISI:000310863400014, title = {Enantioselective synthesis of the essential oil and pheromonal component ar-himachalene by a chiral pool and chirality induction approach}, journal = {Tetrahedron-Asymmetry}, volume = {23}, number = {18-19}, year = {2012}, month = {OCT}, pages = {1410-1415}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

The enantioselective synthesis of both isomers of ar-himachalene has been achieved starting from enantiomerically pure citronellal and p-methyl alpha-methyl styrene as an application of a chiral pool and chirality induction approach, respectively. The key reactions involved in the synthesis include the Sharpless asymmetric dihydroxylation for the induction of chirality at benzylic carbon bearing the methyl group and the use of a hypervalent iodine reagent or trimethylsilyldiazomethane (TMSCHN2) for the six to seven membered ring expansion. (C) 2012 Elsevier Ltd. All rights reserved.

}, issn = {0957-4166}, doi = {10.1016/j.tetasy.2012.09.008}, author = {Chavan, Subhash P. and Khatod, Harshali S.} } @article { ISI:000343624300007, title = {Efficient and mild method for preparation of allylic amines from aziridine-2-alcohols using PPh3/I-2/imidazole}, journal = {Tetrahedron Letters}, volume = {55}, number = {43}, year = {2014}, month = {OCT}, pages = {5905-5907}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Allylic amines are synthesized in good to excellent yields by treatment of aziridine-2-alcohols with PPh3/I-2/imidazole in THF as solvent under mild conditions. (C) 2014 Elsevier Ltd. All rights reserved.

}, keywords = {Chiral allylic amine, Chiral aziridine-2-alcohols, PPh3/iodine/imidazole, Reductive elimination}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2014.08.078}, author = {Chavan, Subhash P. and Khairnar, Lalit B. and Chavan, Prakash N.} } @article { ISI:000355987900093, title = {Enantioselective syntheses of (R)-pipecolic acid, (2R,3R)-3-hydroxypipecolic acid, beta-(+)-conhydrine and (-)-swainsonine using an aziridine derived common chiral synthon}, journal = {RSC Advances}, volume = {5}, number = {62}, year = {2015}, month = {MAY}, pages = {50580-50590}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Concise total syntheses of (R)-pipecolic acid, (R)-ethyl-6-oxopipecolate, (2R, 3R)-3-hydroxypipecolic acid and formal syntheses of beta-(+)-conhydrine, (-)-lentiginosine, (-)-swainsonine and 1,2-di-epi-swainsonine have been accomplished starting from a common chiral synthon. The present strategy employs regioselective aziridine ring opening, Wittig olefination and RCM as the key chemical transformations.

}, issn = {2046-2069}, doi = {10.1039/c5ra06429e}, author = {Chavan, Subhash P. and Khairnar, Lalit B. and Pawar, Kailash P. and Chavan, Prakash N. and Kawale, Sanket A.} } @article { ISI:000377515200041, title = {Exploration of the diastereoselectivity in an unusual Grignard reaction and its application towards the synthesis of styryl lactones 7-epi-(+)-goniodiol and 8-epi-(-)-goniodiol}, journal = {RSC Advances}, volume = {6}, number = {56}, year = {2016}, month = {MAY}, pages = {50721-50725}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

An unusual diastereoselective Grignard reaction is explored, where the Grignard reagents are derived from 1,n-dihaloalkanes. A steric bias due to the presence of a quaternary centre adjacent to the acetonide ester at the benzylic position is responsible for the formation of an intramolecularly reduced product in almost quantitative yield. This steric hindrance is responsible for the diastereoselectivity observed with a variety of aromatic as well as aliphatic esters. The unusual Grignard reaction furnishes long chain secondary alcohols possessing a terminal olefin, which are synthetically important intermediates. As an application of this method, the diastereoselective synthesis of styryl lactones viz. 7-epi-(+)-goniodiol (29) and 8-epi(-)-goniodiol (30) has been achieved.

}, issn = {2046-2069}, doi = {10.1039/c6ra03192g}, author = {Chavan, Subhash P. and Khatod, Harshali S. and Das, Tamal and Vanka, Kumar} } @article {46435, title = {Enantioselective formal total synthesis of (-)-quinagolide}, journal = {Organic Letters}, volume = {21}, year = {2019}, month = {NOV}, pages = {9089-9093}, type = {Article}, abstract = {

The enantioselective formal total synthesis of (-)-quinagolide has been accomplished in a linear sequence of 8 purification steps from pyridine. The key steps are (a) organocatalyzed Diets-Alder reaction for fixing all three stereocenters on piperidine ring; (b) protecting group enabled deoxygenation of isoquinuclidine skeleton under Birch reduction condition; (c) Lewis acid (TiCl4) catalyzed intramolecular Friedel-Crafts cyclization of dicarboxylic acid; and (d) one-pot diastereoselective ketone reduction-intramolecular cyclization to form oxazolidinone which enables trans-geometry installation. During the course of the synthesis, an interesting reductive cleavage of the C-N bond in the electron-deficient isoquinuclidine skeleton under the Birch reduction conditions has been observed. This is the first synthetic effort to access the core skeleton of (-)-quinagolide.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.9b03477}, author = {Chavan, Subhash P. and Kadam, Appasaheb L. and Gonnade, Rajesh G.} } @article {46913, title = {Enolate-mediated regioselective synthesis of 1,2,3-triazoles via azide-aldehydes or ketones [3+2]-cycloaddition reactions in aqueous phase}, journal = {Tetrahedron Letters}, volume = {61}, year = {2020}, month = {MAR}, pages = {151662}, type = {Article}, abstract = {

A synthetic route for the direct conversion of arylazides into the corresponding trizoles via phase transfer catalyst-assisted [3+2] cycloaddition reaction under basic conditions in aqueous medium is reported. This synthetic methodology, which offers high yields and excellent regioselectivity for varieties of triazoles at 100 degrees C for 24 h-48 h and this {\textquoteleft}greener{\textquoteright} synthesis constitutes an alternative to the previously reported well established click reactions. Published by Elsevier Ltd.

}, keywords = {Azides plus aldehydes or ketones, Click chemistry, triazoles, Water}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2020.151662}, author = {Tripathi, Anupam and Rode, V, Chandrashekhar and Llop, Jordi and Chavan, Subhash P. and Joshi, Sameer M.} }