Publications by authors named "Meganathan Nandakumar"

Despite their widespread impact on human health, there are no approved drugs for combating alphavirus infections. The heterocyclic β-aminomethyl vinyl sulfone RA-0002034 () is a potent irreversible covalent inhibitor of the alphavirus nsP2 cysteine protease with broad-spectrum antiviral activity. Analogs of that varied each of the three regions of the molecule were synthesized to establish structure-activity relationships for the inhibition of (CHIKV) nsP2 protease and viral replication.

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Tuberculosis (TB) control is complicated by the emergence of drug resistance. Promising strategies to prevent drug resistance are the targeting of nonreplicating, drug-tolerant bacterial populations and targeting of the host, but inhibitors and targets for either are still rare. In a cell-based screen of ATP-competitive inhibitors, we identified compounds with in vitro activity against replicating (), and an anilinoquinazoline (AQA) that also had potent activity against nonreplicating and persistent .

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Site-selective functionalization of unactivated C(sp)-H centers is challenging because of the ubiquity and strength of alkyl C-H bonds. Herein, we disclose a position-selective C(sp)-C(sp) cross-coupling reaction. This process engages C(sp)-H bonds and aryl bromides, utilizing catalytic quantities of a photoredox-capable molecule and a nickel precatalyst.

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For more than 70 years, nitrogen-centered radicals have been recognized as potent synthetic intermediates. This review is a survey designed for use by chemists engaged in target-oriented synthesis. This review summarizes the recent paradigm shift in access to and application of -centered radicals enabled by visible-light photocatalysis.

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Stereogenic trifluoromethyl-substituted carbon centers are highly sought-after moieties in pharmaceutical and agrochemical discovery. Here, we show that lithiation-borylation reactions of 2-trifluoromethyl oxirane give densely functionalized and highly versatile trifluoromethyl-substituted α-tertiary boronic esters. The intermediate boronate complexes undergo the desired 1,2-rearrangement of the carbon-based group with complete retentive stereospecificity, a process that was only observed in non-polar solvents in the presence of TESOTf.

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An enantiodivergent method for the synthesis of multiply substituted allenes is described. Highly enantioenriched, point-chiral boronic esters were synthesized by homologation of α-seleno alkenyl boronic esters with lithiated carbamates and eliminated to form axially chiral allene products. By employing either oxidative or alkylative conditions, both syn and anti elimination could be achieved with complete stereospecificity.

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In the title 1-oxo-1,2-di-hydro-naphthalene derivatives, CHO, (I), CHOS, (II), and CHOS, (III), the cyclo-hexa-1,3-diene rings of the 1,2-di-hydro-naphthalene ring systems adopt half-chair, boat and half-chair conformations, respectively. The carbonyl O atoms attached to the di-hydro-naphthalene ring systems are each significantly deviated from the mean plane of the 1,2-di-hydro-naphthalene ring system, by 0.6162 (12) Å in (I), 0.

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1,3-Diarylisobenzofuran-DMAD adducts upon reaction with BF3·OEt2 in DCM at room temperature underwent a regiospecific 1,2-aryl migration followed by the Krapcho decarboxylation to give tri-substituted α-naphthols in good yields.

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The title compounds, C21H16O2S2 (I) and C25H20O2 (II), are products of a tandem 'pincer' Diels-Alder reaction consisting of [2 + 2] cyclo-additions between benzo[c]furan and cyclo-penta-none. Each comprises a fused tetra-cyclic ring system containing two five-membered rings (in envelope conformations with the O atom as the flap) and six-membered rings (in boat conformations). In addition, two thio-phene rings in (I) and two phenyl rings in (II) are attached to the tetra-cyclic ring system.

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The title compound, C28H18O2S, is composed of a naphthalene ring system fused with a benzo-thio-phene ring and attached to two phenyl rings. The phenyl rings make dihedral angles of 70.92 (8) and 79.

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The asymmetric unit of the title compound, C49H36O6·CHCl3, contains half an organic mol-ecule, the complete mol-ecule being generated by the operation of a crystallographic twofold rotation axis, and half a highly disordered chloro-form mol-ecule. The contribution to the diffraction pattern of the latter was removed using the program SQUEEZE in PLATON [Spek (2009 ▶). Acta Cryst.

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One pot syntheses of substituted dibenzothiophene S,S-dioxides and fluorenones were successfully achieved by Diels-Alder reaction of benzo[c]furans with thiophene S,S-dioxides and indenones, respectively. Photophysical properties of representative seven- and nine-membered dibenzothiophene S,S-dioxide acenes were also reported.

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The title compound, C28H24O5, consists of a fused tricyclic system containing two five-membered rings and one six-membered ring. The five-membered rings both exhibit an envelope conformation with the O atom at the flap, whereas the six-membered ring adopts a boat conformation. The dihedral angle between the 4-methyl-phenyl rings at the 1,8-positions is 76.

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The title compound, C30H30O5, is the Diels-Alder adduct from 1,3-diphenyl-benzo[c]furan and diethyl maleate. The mol-ecule comprises a fused tricyclic system containing two five-membered rings, which are in envelope conformations with the O atom at the flap, and a six-membered ring adopting a boat conformation. The dihedral angle between the 4-methyl-phenyl substituents in the 1- and 8-positions is 62.

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The title compound, C25H20O5S, is the product of a Diels-Alder reaction. The mol-ecule consists of a fused tricyclic system containing two five-membered rings and one six-membered ring. The five-membered rings both show an envelope conformation with the O atom at the flap, whereas the six-membered ring adopts a boat conformation.

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The title compound, C28H26O5, is the Diels-Alder adduct from 1,3-diphenyl-benzo[c]furan and diethyl maleate. The mol-ecule comprises of a fused tricyclic system containing two five-membered rings, which are in envelope conformations with the O atom at the flap, and a six-membered ring adopting a boat conformation. The dihedral angle between phenyl substituents in the 1,8-positions is 55.

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A ZnBr(2)-mediated regioselective annulation of unsymmetrical 1,2-diarylmethinedipivalates in DCM at room temperature led to the formation of annulated arenes and heteroarenes. The annulation of the dipivalate proceeds through the intermediacy of benzylic carbocations followed by intramolecular cyclization and subsequent aromatization to give the annulated products. The annulation methodology is highly efficient for the syntheses of anthracene as well as naphtho[b]thiophene analogues.

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In the title compound, C(40)H(44)O(3), the fluorene ring system is essentially planar, with a maximum deviation of 0.075 (3) Å, and forms dihedral angles of 70.62 (8) and 70.

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The asymmetric unit of the title compound, C(22)H(18)O(2), contains one half-mol-ecule, the complete mol-ecule being generated by the operation of a crystallographic twofold rotation axis. The carbonyl group and the two C atoms attached to it forms inter-planar angles of 23.67 (7)° with the methyl-substituted phenyl ring and 50.

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In the title compound, C(26)H(24)O(2), the crowded naphthalene ring system is essentially planar [maximum deviation of 0.027 (2) Å for one of the C atoms of the unsubstituted ring]. In the crystal, mol-ecules are connected by O-H⋯O hydrogen bonds into chains along the a axis.

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A facile preparation of arylmethyl and heteroarylmethyl phosphonate esters was achieved involving a Lewis acid mediated Michaelis-Arbuzov reaction at room temperature. Interaction of arylmethyl halides/alcohols with triethyl phosphite in the presence of Lewis acid at room temperature afforded phosphonate esters in good yields.

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