@article { ISI:000246298900004, title = {Practical formal synthesis of D-(+)-biotin from 4-formylazetidin-2-one}, journal = {Synthesis-Stuttgart}, number = {8}, year = {2007}, month = {APR}, pages = {1159-1164}, publisher = {GEORG THIEME VERLAG KG}, type = {Article}, address = {RUDIGERSTR 14, D-70469 STUTTGART, GERMANY}, abstract = {

A practical synthesis of (3S,6R)-1,3-dibenzyltetrahydro-1H-furo[3,4-d]imidazole-2,4-dione, an important intermediate in the synthesis of biotin, from 4-formyl-3-mesyloxyazetidin-2-one has been achieved. Acid-catalyzed azetidin-2-one ring opening followed by a one-pot conversion of diamine hydrochloride to a cyclic urea and hydroxymethylene to chloromethylene by triphosgene to obtain (4S,5R)-methyl-1,3-dibenzyl-5-chloromethyl-2-oxoimidazolidine-4-carboxyl ate is the key step in this synthesis.

}, keywords = {azetidin-2-one, beta-Lactams, cyclization, Lactone, reduction}, issn = {0039-7881}, doi = {10.1055/s-2007-965992}, author = {Kale, Ajaykumar S. and Puranik, Vedavati G. and Deshmukh, Abdul Rakeeb A. S.} } @article { ISI:000284515800005, title = {Combined experimental and density functional theory study on the Pd-mediated cycloisomerization of o-alkynylnitrobenzenes - synthesis of isatogens and their evaluation as modulators of ROS-mediated cell death}, journal = {European Journal of Organic Chemistry}, number = {31}, year = {2010}, month = {NOV}, pages = {5955-5966}, publisher = {WILEY-V C H VERLAG GMBH}, address = {PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY}, abstract = {

Highly selective cycloisomerization of o-alkynylnitrobenzenes, leading to isatogens, has been achieved by employment of a Pd-II complex. This reaction is very general and functional-group-tolerant. The possible mechanism of this reaction was investigated with the help of DFT calculations. Three possible pathways - namely, the addition of the nitro group either in (i) 5-exo-dig or (ii) 6-endo-dig mode and (iii) halopalladation - and subsequent intramolecular events have been considered and studied in detail. These investigations revealed that pathway (i) is the favored route to isatogen formation. A preliminary screening of the available isatogens reveals the 2-alkylisatogens to be novel ROS scavengers capable of inhibiting cellular necroptosis.

}, keywords = {Anthranil, cyclization, Density functional calculations, isatogens, Nitro-alkyne cycloisomerization, Palladium}, issn = {1434-193X}, doi = {10.1002/ejoc.201000769}, author = {Ramana, Chepuri V. and Patel, Pitambar and Vanka, Kumar and Miao, Benchun and Degterev, Alexei} } @article { ISI:000308778100017, title = {Highly diastereoselective total synthesis of (+/-)-heritonin and (+/-)-heritol}, journal = {Tetrahedron}, volume = {68}, number = {40}, year = {2012}, month = {OCT}, pages = {8509-8514}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

A highly diastereoselective synthesis of heritol and heritonin by intramolecular cyclization on a preformed sensitive butenolide functionality is described. (C) 2012 Elsevier Ltd. All rights reserved.

}, keywords = {Butenolide, cyclization, Dihydroxylation, Friedel-Crafts acylation, Tetralone}, issn = {0040-4020}, doi = {10.1016/j.tet.2012.07.020}, author = {Chavan, Subhash P. and Garai, Sumanta and Kalkote, Uttam R.} } @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:000316095000011, title = {Target cum flexibility: simple access to benzofuran conjugated sugar and nucleoside derivatives}, journal = {Tetrahedron Letters}, volume = {54}, number = {14}, year = {2013}, month = {APR}, pages = {1824-1827}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

The [Pd]-catalyzed domino process comprising of the coupling of alkynes and o-iodophenol and the subsequent cyclization leading to benzofurans has been successfully applied on the sugar and nucleoside derived alkynes. (C) 2013 Elsevier Ltd. All rights reserved.

}, keywords = {Benzofuran, carbohydrates, cyclization, Nucleoside, Palladium}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2013.01.089}, author = {Kommagalla, Yadagiri and Srinivas, Kolluru and Ramana, C. V.} } @article { ISI:000335152300007, title = {Croncise organocatalytic route to protected (2S, 4R)-4-hydroxyornithine and(+)-pseudohygroline}, journal = {Synlett}, volume = {25}, number = {8}, year = {2014}, month = {MAY}, pages = {1089-1092}, publisher = {GEORG THIEME VERLAG KG}, address = {RUDIGERSTR 14, D-70469 STUTTGART, GERMANY}, abstract = {

A practical, efficient, and organocatalytic approach to the synthesis of (2S,4R)-4-hydroxyornithine and (+)-pseudohygroline is reported using proline-catalyzed sequential alpha-aminoxylation/alpha-amination reaction and Horner-Wadsworth-Emmons olefination reaction of an aldehyde as the key step.

}, keywords = {aldehydes, Amination, Amino alcohols, cyclization, Enantioselectivity, Wittig reaction}, issn = {0936-5214}, doi = {10.1055/s-0033-1340977}, author = {Jha, Vishwajeet and Kumar, Pradeep} } @article { ISI:000328606500014, title = {One-pot synthesis of cyclic carbonates from aldehydes, sulfur ylide, and CO2}, journal = {Synlett}, volume = {25}, number = {1}, year = {2014}, month = {JAN}, pages = {97-101}, publisher = {GEORG THIEME VERLAG KG}, address = {RUDIGERSTR 14, D-70469 STUTTGART, GERMANY}, abstract = {

Treatment of aldehydes with sulfur ylide (CH2=SOMe2 or CH2=SMe2), in the presence of CO2 (1 atm) bubbled sequentially under mild conditions, produces cyclic carbonates in preparative yields. Sodium iodide formed in situ promotes the reaction between epoxide as intermediate and CO2 at ambient conditions, thus constituting a powerful metal-free synthesis of organic cyclic carbonates directly from aldehydes.

}, keywords = {Carbon dioxide, cyclic carbonates, cyclization, epoxides, Insertion}, issn = {0936-5214}, doi = {10.1055/s-0033-1340072}, author = {Aher, Ravindra D. and Kumar, B. Senthil and Sudalai, Arumugam} } @article { ISI:000342568800011, title = {Synthesis of (+)-harmicine}, journal = {Synthesis-Stuttgart}, volume = {46}, number = {19}, year = {2014}, month = {OCT}, pages = {2591-2594}, publisher = {GEORG THIEME VERLAG KG}, address = {RUDIGERSTR 14, D-70469 STUTTGART, GERMANY}, abstract = {

A facile convergent access to the important indole alkaloid (+)-harmicine is described, starting from tryptamine and (R)-acetoxysuccinic anhydride via the corresponding acetoxysuccinimide in very good overall yield. Regioselective reduction of an unsymmetrical imide carbonyl group and acid-catalyzed stereoselective intramolecular cyclization were the key features involved. The directing group to induce asymmetry was finally detached via the corresponding iodide by using tributyltin hydride chemistry.

}, keywords = {alkaloids, cyclization, imides, reduction, stereoselective synthesis}, issn = {0039-7881}, doi = {10.1055/s-0034-1378381}, author = {Mondal, Pravat and N. P. Argade} } @article { ISI:000349061500011, title = {Formal syntheses of (2R,3R)-3-hydroxy pipecolic acid and (2R,3S)-3-hydroxy pipecolic acid from L-ascorbic acid}, journal = {Tetrahedron Letters}, volume = {56}, number = {6}, year = {2015}, month = {FEB}, pages = {805-807}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Formal syntheses of both cis and trans 3-hydroxy pipecolic acids is achieved from L-ascorbic acid. Present synthesis describes use of chiral pool approach in which epimerization, Staudinger reaction and Cyclization reactions were employed as key steps. (C) 2014 Elsevier Ltd. All rights reserved.

}, keywords = {3-Hydroxy pipecolic acid, cyclization, Epimerization, L-Ascorbic acid}, issn = {0040-4039}, doi = {10.1016/j.tetlet.2014.12.103}, author = {Chavan, Subhash P. and Dumare, Nilesh B. and Pawar, Kailash P.} } @article { ISI:000351584500007, title = {Synthesis of 3-ethyl-4-metyl-1h,5-dihydro-2h-pyrrol-2-one by novel palladium(ii)-catalyzed cyclization and ring-closing metathesis}, journal = {Synthesis-Stuttgart}, volume = {47}, number = {7}, year = {2015}, month = {APR}, pages = {955-960}, publisher = {GEORG THIEME VERLAG KG}, type = {Article}, address = {RUDIGERSTR 14, D-70469 STUTTGART, GERMANY}, abstract = {

Synthesis of 3-ethyl-4-methyl-1,5-dihydro-2H-pyrrol-2-one is described starting from commercially available allylamine and 4-methoxybenzylamine employing palladium-catalyzed cyclization or ring-closing metathesis as the key steps.

}, keywords = {antidiabetic, cyclization, glimepiride, lactams, metabolite, pyrrolinone, Ring-closing metathesis}, issn = {0039-7881}, doi = {10.1055/s-0034-1379985}, author = {Chavan, Subhash P. and Pathak, Ashok B. and Pawar, Kailash P.} } @article {46628, title = {Apparent umpolung reactivity of indole through [Au]-catalysed cyclisation and lewis-acid-mediated allylation}, journal = {Chemistry-A European Journal}, volume = {26}, year = {2020}, month = {DEC}, pages = {17171-17175}, type = {Article}, abstract = {

The sequential functionalization of indole C2 and C3 in an umpolung fashion was executed with a predesigned substrate and choice of reagents. The developed method comprises gold-catalysed alkynol cycloisomerisation/intramolecular addition of C2 of indole and subsequent BF3.OEt2-mediated regioselective C3 allylation, resulting in the synthesis of the functionalized indoloisoquinolinone scaffold. The reaction involves 5-endo-alkynol cycloisomerisation and the dearomative addition of indole C2 to the intermediate oxocarbenium cation, which results in two equilibrating fused and spiropentacyclic intermediates, which upon treatment with allyl silane in the presence of BF3.OEt2, undergo selective indole C3 allylation. Other nucleophiles, such as hydride, azide and indole, were also found to be compatible with this process.

}, keywords = {Allylation, cyclization, domino reactions, Gold, umpolung}, issn = {0947-6539}, doi = {10.1002/chem.202003441, Early Access Date = NOV 2020}, author = {Shinde, Mahesh H. and Ramana, Chepuri V.} } @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 {48718, title = {Rapid bioinspired N-acyliminium ion strategy for the ABC core of the stemona alkaloids}, journal = {Asian Journal of Organic Chemistry}, volume = {12}, year = {2023}, month = {SEP}, type = {Article}, abstract = {

A concise and highly diastereoselective bioinspired key cationic cyclization strategy for the asymmetric synthesis of the tricyclic core of the (-)-stemoamide, together with 8,9-bis-epi-stemoamide has been described. The key N-acyliminium ion precursors were accessed from L-tartaric acid and L-malic acid respectively. The use of ethyl acetoacetate derived bifunctional allylidenetriphenylphosphorane reagent in the early stage of the synthetic strategy is advantageous for the rapid construction of highly functionalized key pyrrolo[1,2-\& alpha;]azepine frameworks.

}, keywords = {alkaloids, Biomimetic synthesis, Claisen rearrangement, cyclization, Regioselectivity}, issn = {2193-5807}, doi = {10.1002/ajoc.202300331}, author = {Chavan, Subhash P. and Kalbhor, Dinesh B. and Gonnade, Rajesh G.} }