00976nas a2200145 4500008004100000245011000041210006900151260000800220300001400228490000700242520040600249100002300655700002100678856013100699 2017 eng d00aExploiting the dual role of ethynylbenziodoxolones in gold-catalyzed C(sp)-C(sp) cross-coupling reactions0 aExploiting the dual role of ethynylbenziodoxolones in goldcataly cJUL a7937-79400 v533 aReported herein is the gold-catalyzed alkynylation of terminal alkynes using ethynylbenziodoxolones (EBXs), where EBXs serve a dual role as oxidants as well as alkyne transfer agents to access unsymmetrical 1,3-diynes. Hence, the catalytic system requires no external oxidants and is compatible with a broad range of substrates, including those with polar functional groups such as NH, OHand B(OH)(2).1 aBanerjee, Somsuvra1 aPatil, Nitin, T. uhttps://library.ncl.res.in/content/exploiting-dual-role-ethynylbenziodoxolones-gold-catalyzed-csp-csp-cross-coupling-reactions01530nas a2200193 4500008004100000020001400041245008900055210006900144260000800213300001600221490000700237520087000244100002201114700002301136700002301159700001801182700002101200856011501221 2018 eng d a1359-734500a Oxidant-free oxidative gold catalysis: the new paradigm in cross-coupling reactions0 aOxidantfree oxidative gold catalysis the new paradigm in crossco cOCT a11069-110830 v543 a

The construction of C-C and C-X (X = hetero atom) bonds is the core aspect for the assembly of molecules. In this regard, late transition-metal-catalyzed cross-coupling reactions have retained their dominance for decades. Lately, gold catalysts have been emerging as a reliable contender for such transformations owing to the recent findings that reveal gold's potential beyond carbophilic -Lewis acid. The newfound ability of gold to undergo redox transformations under certain circumstances has allowed us to explore gold catalysts as a viable alternative to other late transition-metals for efficient construction of cross-coupled products. This feature article critically presents an overview of all the redox neutral cross-coupling reactions enabled by gold catalysis, which we believe would stimulate further research activities in this promising area.

1 aAkram, Manjur, O.1 aBanerjee, Somsuvra1 aSaswade, Sagar, S.1 aBedi, Vaibhav1 aPatil, Nitin, T. uhttps://library.ncl.res.in/content/oxidant-free-oxidative-gold-catalysis-new-paradigm-cross-coupling-reactions01514nas a2200193 4500008004100000022001400041245020700055210006900262260000900331300001400340490000700354520072300361100002201084700002301106700002301129700001701152700002101169856013001190 2019 eng d a0022-326300aExternal oxidant-dependent reactivity switch in copper-mediated intramolecular carboamination of alkynes: access to a different class of fluorescent ionic nitrogen-doped polycyclic aromatic hydrocarbons0 aExternal oxidantdependent reactivity switch in coppermediated in cAPR  a4120-41300 v843 a

An interesting case of external oxidant-controlled reactivity switch leading to a divergent set of ionic nitrogen-doped polycyclic aromatic hydrocarbons (N-doped PAHs), is presented here, which is quite unrecognized in copper-mediated reactions. In the current scenario, from the same pyridino-alkyne substrates, the use of the external oxidant Ph1(0Ac)2, in combination with Cu(OTf)(2), gave N-doped spiro-PAHs via a dearomative 1,2-carboamination process; whereas, without the use of oxidant, an alkyne/azadiene [4 + 2]-cycloaddition cascade occurred to exclusively afford ionic N-doped PAHs. These newly synthesized N-doped PAHs further exhibit tunable emissions, as well as excellent quantum efficiencies.

1 aShaikh, Aslam, C.1 aBanerjee, Somsuvra1 aMule, Ravindra, D.1 aBera, Saibal1 aPatil, Nitin, T. uhttps://library.ncl.res.in/content/external-oxidant-dependent-reactivity-switch-copper-mediated-intramolecular-carboamination01164nas a2200169 4500008004100000022001400041245008500055210006900140260000800209300001200217490000700229520057800236100002300814700002500837700002100862856011100883 2019 eng d a1523-706000aGold-catalyzed 1,2-oxyalkynylation of N-Allenamides with ethylnylbenziodoxolones0 aGoldcatalyzed 12oxyalkynylation of NAllenamides with ethylnylben cJAN a180-1840 v213 a

A gold-catalyzed 1,2-oxyalkynylation of N-allenamides with ethylnylbenziodoxolones (EBXs) has been achieved for the first time. The reaction, which follows a redox-neutral Au(I)/Au(III) catalytic pathway, was enabled in an attempt to exhaust the EBX reagents atom-economically by putting the nucleophilic carboxylate part of EBXs to appropriate use. This constitutes the first example for gold-catalyzed beta-alkynylation of N-allenamides to construct highly valuable 1,3-enynes. The potential of the sequence is further documented by some follow-up transformations.

1 aBanerjee, Somsuvra1 aSenthilkumar, Beeran1 aPatil, Nitin, T. uhttps://library.ncl.res.in/content/gold-catalyzed-12-oxyalkynylation-n-allenamides-ethylnylbenziodoxolones02414nas a2200205 4500008004100000022001400041245009600055210006900151260000900220300001400229490000700243520169500250100002201945700002401967700002301991700002302014700002502037700002102062856012502083 2019 eng d a0022-326300aIonic pyridinium-oxazole dyads: design, synthesis, and application in mitochondrial imaging0 aIonic pyridiniumoxazole dyads design synthesis and application i cFEB  a1766-17770 v843 a

We recently developed an oxidative intramolecular 1,2-amino-oxygenation reaction, combining gold(I)/gold(III) catalysis, for accessing structurally unique ionic pyridinium-oxazole dyads (PODs) with tunable emission wavelengths. On further investigation, these fluorophores turned out to be potential biomarkers; in particular, the one containing -NMe2 functionality (NMe2-POD) was highly selective for mitochondrial imaging. Of note, because of mitochondria's involvement in early-stage apoptosis and degenerative conditions, tracking the dynamics of mitochondrial morphology with such imaging technology has attracted much interest. Along this line, we wanted to build a library of such PODs which are potential mitochondria trackers. However, Au/Selecfluor, our first-generation catalyst system, suffers from undesired fluorination of electronically rich PODs resulting in an inseparable mixture (1:1) of the PODs and their fluorinated derivatives. In our attempt to search for a better alternative to circumvent this issue, we developed a second-generation approach for the synthesis of PODs by employing Cu(II)/PhI(OAC)(2)-mediated oxidative 1,2-amino-oxygenation of alkynes. Thes newly synthesized PODs exhibit tunable emissions as well as excellent quantum efficiency up to 0.96. Further, this powerful process gives rapid access to a library of NMe2-PODs which are potential mitochondrial imaging agents. Out of the library, the randomly chosen POD-3g was studied for cell-imaging experiments which showed high mitochondrial specificity, superior photostability, and appreciable tolerance to microenvironment changes with respect to commercially available MitoTracker green.

1 aShaikh, Aslam, C.1 aVarma, Mokshada, E.1 aMule, Ravindra, D.1 aBanerjee, Somsuvra1 aKulkarni, Prasad, P.1 aPatil, Nitin, T. uhttps://library.ncl.res.in/content/ionic-pyridinium-oxazole-dyads-design-synthesis-and-application-mitochondrial-imaging01355nas a2200169 4500008004100000022001400041245011500055210006900170260000900239300001400248490000700262520071800269100002300987700002301010700002101033856013101054 2020 eng d a1359-734500aGold and hypervalent iodine(iii): liaisons over a decade for electrophilic functional group transfer reactions0 aGold and hypervalent iodineiii liaisons over a decade for electr cMAR  a2677-26900 v563 a

Over the last two decades, hypervalent iodine(iii) reagents have evolved from being `bonding curiosities' to mainstream reagents in organic synthesis, in particular, electrophilic functional group transfer reactions. In this context, gold catalysts have not only emerged as a unique toolbox to facilitate such reactions (especially alkynylations) but also opened new possibilities with their different modes of reactivities for other functional group transfer reactions (acetoxylations and arylations). This feature article critically summarizes hitherto all such Au-catalyzed electrophilic functional group transfer reactions with hypervalent iodine(iii) reagents, emphasizing their mechanistic aspects.

1 aBanerjee, Somsuvra1 aBhoyare, Vivek, W.1 aPatil, Nitin, T. uhttps://library.ncl.res.in/content/gold-and-hypervalent-iodineiii-liaisons-over-decade-electrophilic-functional-group-transfer01280nas a2200193 4500008004100000022001400041245006100055210005900116260000800175300001400183490000700197520066800204100002300872700002600895700002300921700002500944700002100969856009600990 2020 eng d a1523-706000aGold-catalyzed alkynylative meyer-schuster rearrangement0 aGoldcatalyzed alkynylative meyerschuster rearrangement cJUN a4792-47960 v223 a

By applying the ``interplay'' mode, which consolidates two key reactivity modes of gold catalysis, namely pi-activation mode and cross-coupling mode, the first alkynylative Meyer-Schuster rearrangement is designed and successfully implemented. The current protocol gives straightforward access to enynones, a highly valuable building block, from easily available propargyl alcohol feedstocks. Control experiments suggest an Au(III) catalyst triggers the Meyer-Schuster rearrangement, whereas monitoring the reaction with ESI-HRMS provided strong evidence in favor of a key alkynylgold(III) intermediate which supports the proposed ``interplay'' scenario.

1 aBanerjee, Somsuvra1 aAmbegave, Shivhar, B.1 aMule, Ravindra, D.1 aSenthilkumar, Beeran1 aPatil, Nitin, T. uhttps://library.ncl.res.in/content/gold-catalyzed-alkynylative-meyer-schuster-rearrangement01998nas a2200349 4500008004100000022001400041245022500055210006900280260000900349300001500358490000700373520077700380653002301157653001201180653001601192653002201208653002601230653001301256100002301269700001501292700002001307700001901327700001701346700002701363700002201390700002301412700002301435700001801458700002501476700002101501856012601522 2022 eng d a0947-653900aInterplay of anion-pi(+) and pi(+)-pi(+) interactions in novel pyrido[2,1-a]isoquinolinium-based aiegens - substituent- and counterion-dependent fluorescence modulation and applications in live cell mitochondrial imaging0 aInterplay of anionpi and pipi interactions in novel pyrido21aiso cJUL  ae2022006320 v283 a

Recently, the concept of anion-pi(+) interactions has witnessed unique applications in the field of AIEgen development. In this contribution, we disclose a consolidated study of a library of N-doped ionic AIEgens accessed through silver-mediated cyclization of pyridino-alkynes. A thorough photophysical, computational and crystallographic study has been conducted to rationalize the observed substituent- and counterion-dependent fluorescence properties of these luminogens. We further elucidate the prominent role of anion-pi(+) interactions, pi(+)-pi(+) interactions and other non-covalent interactions, in inhibiting the undesired ACQ effect. Finally, we have also demonstrated the application of selected AIEgens for imaging of mitochondria in live cells.

10a1-a]isoquinolinium10aAIEgens10aanion-pi(+)10acrystal structure10amitochondrial imaging10apyrido[21 aMule, Ravindra, D.1 aRoy, Rupam1 aMandal, Koushik1 aChopra, Deepak1 aDutta, Tanoy1 aSancheti, Shashank, P.1 aShinde, Popat, S.1 aBanerjee, Somsuvra1 aKoner, Apurba, Lal1 aBhowal, Rohit1 aSenthilkumar, Beeran1 aPatil, Nitin, T. uhttps://library.ncl.res.in/content/interplay-anion-pi-and-pi-pi-interactions-novel-pyrido21-aisoquinolinium-based-aiegens