@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 {46436, title = {Formal synthesis of brivaracetam: a key to construct the pyrrolidone scaffold using Pd-catalyzed oxidative cyclization and ring-closing metathesis reaction}, journal = {Tetrahedron Letters}, volume = {60}, year = {2019}, month = {NOV}, pages = {151249}, type = {Article}, abstract = {

A short and efficient synthetic approach for brivaracetam has been accomplished via two different routes which utilize Pd-catalyzed oxidative cyclization and ring-closing metathesis (RCM) as the key reaction. These two routes are novel, simple, scalable and rely on (E)-pent-2-en-1-ol and valeraldehyde as a commercially available starting material to yield brivaracetam with good overall yield. (C) 2019 Published by Elsevier Ltd.

}, keywords = {Antiepileptic drugs, Pd-catalyzed oxidative cyclization, pyrrolinone, Ring-closing metathesis reaction}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2019.151249}, author = {Chavan, Subhash P. and Kawale, Sanket A. and Chavan, Prakash N.} } @article {46115, title = {Total synthesis of (+/-)-quinagolide: a potent D-2 receptor agonist for the treatment of hyperprolactinemia}, journal = {ACS Omega}, volume = {4}, year = {2019}, month = {MAY}, pages = {8231-8238}, type = {Article}, abstract = {

A potent dopamine (D-2) receptor agonist (+/-)-quinagolide, which is used for the treatment of hyperprolactinemia, was synthesized using the ring closing metathesis (RCM) approach from meta-hydroxybenzaldehyde as the starting material. The key features of this synthesis are pyrolytic elimination, late-stage expedient synthesis of functionalized trans-fused tetrahydropyridine-3-carboxylates from olefin 6, via conjugate addition-elimination upon acetate 11, followed by RCM and phenyliodine bis(trifluoroacetate) (PIFA)-mediated Hofmann rearrangement of piperidine-3-carboxamide, which enables the synthesis of 3-aminopiperidine skeleton of quinagolide. For the total synthesis of natural products such as ergot alkaloids, late-stage synthesis of functionalized trans-fused tetrahydropyridine-3-carboxylates using RCM and PIFA-mediated Hofmann rearrangement of piperidine-3-carboxamide, which allows quick access to the synthetically challenging 3-aminopiperidine skeleton, are the main achievements of the present work.

}, issn = {2470-1343}, doi = {10.1021/acsomega.9b00903}, author = {Chavan, Subhash P. and Kadam, Appasaheb L. and Kawale, Sanket A.} } @article {47349, title = {Application of allylic amine formation from aziridine-2-ol under appel reaction condition: synthesis of N-(tert-butoxycarbonyl)-D-vinyl glycine methyl ester}, journal = {Tetrahedron Letters}, volume = {73}, year = {2021}, month = {JUN }, pages = {153119}, type = {Article}, abstract = {

PPh3/I-2/imidazolde mediated allyl amine formation from aziridine-2-alcohol was explored for the synthesis of N-(tert-butoxycarbonyl)-D-vinyl glycine methyl ester. (C) 2021 Published by Elsevier Ltd.

}, keywords = {Allyl amine, Aziridine-2-alcohol, Aziridinium ion, Birch reaction, Ring opening}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2021.153119}, author = {Chavan, Subhash P. and Kawale, Sanket A. and Patil, Niteen B. and Kalbhor, Dinesh B.} } @article {47664, title = {Formal synthesis of (-)-quinagolide: diastereoselective ring expansion via a bicyclic aziridinium ion strategy to access the octahydrobenzo[g]quinoline architecture}, journal = {Journal of Organic Chemistry}, volume = {86}, year = {2021}, month = {JUL }, pages = {9344-9352}, type = {Article}, abstract = {The diastereoselective formal synthesis of (-)-quinagolide, a D-2 receptor agonist, has been achieved. The synthesis started from L-pyroglutamic acid and relied on utilization of (a) a stereospecific catalytic hydrogenation and diastereoselective Horner-Emmons-Michael cascade to obtain functionalized prolinate, (b) a Lewis acid mediated Pummerer cyclization to construct a tricyclic fused ring system, and (c) a diastereoselective ring expansion via a bicyclic aziridinium intermediate to access the required 3-substituted piperidine scaffold.}, issn = {0022-3263}, doi = {10.1021/acs.joc.1c00603}, author = {Chavan, Subhash P. and Kawale, Sanket A. and Pisal, Mahesh M. and Kadam, Appasaheb L. and Gonnade, Rajesh G.} } @article {48009, title = {cis-aziridine synthon based synthetic investigation for tamiflu employing horner-wadsworth-emmons reaction}, journal = {European Journal of Organic Chemistry}, volume = {2022}, year = {2022}, month = {JUL }, pages = {e202200384}, type = {Article}, abstract = {

Synthetic investigations to achieve a novel intermediate of Tamiflu by using cis-aziridine as a chiral building block, which is readily synthesized from (D)-mannitol as a renewable starting material, has been presented. The present approach utilizes the intramolecular Horner-Wadsworth-Emmons reaction as the key step for the synthesis of Tamiflu. On the other hand, diene containing allylic aziridine framework is found to be inefficient to furnish the six-membered core skeleton of Tamiflu through ring-closing metathesis reaction.

}, keywords = {Aziridine, cyclization, HWE reaction, Metathesis, Tamiflu}, issn = {1434-193X}, doi = {10.1002/ejoc.202200384}, author = {Chavan, Subhash P. and Kawale, Sanket A. and Gonnade, Rajesh G.} } @article {48075, title = {Revisiting classical pummerer cyclization reaction: a key strategy for the synthesis of (+/-)-quinagolide}, journal = {ChemistrySelect}, volume = {7}, year = {2022}, month = {JUL}, pages = {e202201600}, type = {Article}, abstract = {

A formal synthesis of (+/-)-quinagolide using beta-alanine as a starting material has been achieved. Late stage intramolecular classical Pummerer reaction has been used as a key synthetic tool to construct octahydrobenzo[g]quinoline skeleton of quinagolide. Conjugative reduction of olefin, regioselective C-alkylation over O-alkylation of beta-ketoester followed by retro-Dieckmann/ Dieckmann reaction sequence has been used as a key reaction sequence to achieve prerequisite sulfoxide for the Pummerer reaction. While revisiting the classical Pummerer reaction, the one-pot sequential thionium ion induced cyclocarbamation followed by N-carbamate deprotection and Friedel-Crafts type Pummerer cyclization was observed as an important finding of the present work.

}, keywords = {Alkylation, Cyclocarbamation, Hyperprolactinemia, rearrangement, Thionium ion}, issn = {2365-6549}, doi = {10.1002/slct.202201600}, author = {Chavan, Subhash P. and Kawale, Sanket A. and Tripathi, Anupam and Kadam, Appasaheb L. and Gonnade, Rajesh G.} }