@article {44192, title = {Synthesis of furo[2,3-b]pyran-2-ones through Ag(I)- or Ag(I)-Au(I)-catalyzed cascade annulation of alkynols and alpha-ketoesters}, journal = {Organic Letters}, volume = {20}, year = {2018}, month = {FEB }, pages = {872-875}, type = {Article}, abstract = {

Ag(I)- or Ag(I)-Au(I)-catalyzed cascade annulation of alkynols (5-hexyn-1-ol systems) with a-ketoesters involving a dual activation process (pi and sigma) has been developed for the first time. This reaction proceeds through cycloisomerization of alkynol to give the 6-endo-enol ether followed by annulation with an alpha-ketoester to furnish furo[2,3-b]pyran-2-ones in good yields. Chemical structures of all products were rigorously confirmed by single crystal X-ray analysis and analogy.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.7b04027}, author = {Thorat, Sagar S. and Kataria, Priyanka and Kontham, Ravindar} } @article {47642, title = {Studies directed toward the synthesis of hedycoropyrans: total synthesis of des-hydroxy (-)-hedycoropyran B (ent-rhoiptelol B)}, journal = {Organic \& Biomolecular Chemistry}, volume = {20}, year = {2022}, month = {JAN }, pages = {444-463}, type = {Article}, abstract = {A full account of our efforts directed towards the synthesis of the diarylheptanoid-derived natural products hedycoropyrans that led to the total synthesis of ent-rhoiptelol B is described. In this endeavor, we have attempted two distinct synthetic strategies to access hedycoropyrans A and B, which led us to establish a facile synthetic route for des-hydroxy (-)-hedycoropyran B (ent-rhoiptelol B) from simple and readily accessible building blocks of 4-allylanisole and vanillin, employing Sharpless asymmetric epoxidation, CBS reduction, and an intramolecular AgOTf-catalyzed oxa-Michael reaction of suitably functionalized hydroxy-ynone as key transformations. The investigations disclosed herein will provide insights into designing novel synthetic routes for THP-DAH-derived natural products.}, issn = {1477-0520}, doi = {10.1039/d1ob01972d}, author = {Kataria, Priyanka and Nomula, Rajesh and Kontham, Ravindar} } @article {48709, title = {Bi(III)-catalyzed synthesis of substituted furans from hydroxy-oxetanyl ketones: application to unified total synthesis of shikonofurans J, D, E, and C}, journal = {Journal of Organic Chemistry}, volume = {88}, year = {2023}, month = {MAY}, pages = {7328-7346}, type = {Article}, abstract = {

We report an improved synthetic protocol for hydroxymethyl-derivedpolysubstituted furans employing Bi-(III)-catalyzed dehydrative cycloisomerizationof alpha-hydroxy oxetanyl ketones. This procedure provides rapidaccess (within 5 min) to highly substituted furans with exceptionalfunctional group diversity, excellent yields, generality, scalability,and operationally simple reaction conditions. Further, it demonstratedthe utility of this method in the first enantioselective total synthesisof furyl-hydroquinone-derived biologically potent natural productsshikonofurans J, D, E, and C in seven linear steps, starting fromreadily available building blocks of 2,5-dihydroxy acetophenone and3-oxetanone employing chiral-phosphoric acid (TRIP)-catalyzed asymmetricprenylation as a key step to induce the chirality.

}, issn = {0022-3263}, doi = {10.1021/acs.joc.3c00549}, author = {Kataria, Priyanka and Sahoo, Shubhranshu Shekhar and Kontham, Ravindar} } @article {49036, title = {Concise and collective total syntheses of 2,4-disubstituted furan-derived natural products from hydroxyoxetanyl ketones}, journal = {Organic and biomolecular chemistry}, volume = {22}, year = {2024}, month = {FEB }, pages = {1475-1483}, type = {Article}, abstract = {

The furan moiety, prevalent in bioactive natural products and essential drugs, presents intriguing structural features that have spurred our exploration into streamlined chemical synthesis routes for related natural products. In this study, we demonstrate the concise total synthesis of eight 2,4-disubstituted furan-derived natural products (including methylfuroic acid, rabdoketones A and B, paleofurans A and B, tournefolin C, and shikonofurans A and B). Our methodology revolves around the utilization of hydroxyoxetanyl ketones as pivotal intermediates. The approach encompasses transformations such as selective organo-catalyzed cross-ketol addition, synthesis of hydroxymethyl-tethered furans through Bi(OTf)3 catalyzed dehydrative cycloisomerization of alpha-hydroxyoxetanyl ketones, and a hydrogen atom transfer (HAT)-mediated oxidation of primary alcohols into the corresponding acids. This comprehensive synthetic strategy highlights the versatility of hydroxyoxetanyl ketones as invaluable building blocks in the synthesis of furan-containing natural products. A unified total synthesis of eight 2,4-disubstituted furan-derived natural products has been achieved through Bi(iii)-catalyzed cascade cycloisomerization of alpha-hydroxyoxetanyl ketones and hydrogen atom transfer-mediated oxidation of primary alcohols as pivotal transformations.

}, issn = {1477-0520}, doi = {10.1039/d3ob01924a}, author = {Sahoo, Shubhranshu Shekhar and Kataria, Priyanka and Kontham, Ravindar} } @article {49028, title = {Divergent access to polycyclic spiro- and fused-N,O-ketals through Bi(OTf)3-catalyzed [4+2]-annulation of cyclic N-sulfonyl ketimines and alkynols}, journal = {Chemical Communications}, volume = {60}, year = {2024}, month = {JAN}, pages = {1144-1147}, type = {Article}, abstract = {

Bismuth(iii) triflate-catalyzed [4+2]-annulation of cyclic N-sulfonyl ketimines (derived from saccharin) and alkynyl alcohols (4-pentyn-1-ols and 5-hexyn-1-ols) has been reported. This cascade annulation provides a diverse array of polycyclic spiro-and-fused N,O-ketals with excellent substrate scope, good isolated yields, and diastereoselectivities under mild reaction conditions.

}, issn = {1359-7345}, doi = {10.1039/d3cc05599j}, author = {Nakate, Ashwini K. and Kataria, Priyanka and Sambherao, Pooja I. and Krishna, Gamidi Rama and Kontham, Ravindar} }