H. Surya Prakash Rao

Facile Reduction of Azides with Sodium Borohydride/Copper (II) Sulphate System

Abstract Sodium borohydride/copper (II) sulphate reduces alkyl and aryl azides to primary amines and aroyl azides to amides under mild conditions.

One-pot synthesis of pyrrole derivatives from (E)-1,4-diaryl-2-butene-1,4-diones

Abstract 2,5-Di- and 1,2,5-trisubstituted pyrrole derivatives can be prepared conveniently from ( E )-1,4-diaryl-2-butene-1,4-diones in a one-pot operation through domino-pathways via palladium-assisted transfer hydrogenation followed by a Paal–Knorr reaction using ammonium formate and its analogs.

Synthesis of lactones of ortho-tyrosine, DOPA isomers and tryptophan-ortho-tyrosine hybrid amino acids

A new high-yielding syntheses of lactones of ortho-tyrosine, four isomers of DOPA and a hybrid amino acid incorporating tryptophan and ortho-tyrosine have been achieved in a two step sequence from 2-methylamino-3-nitro-4-methylsulfanyl 4H-chromenes 7. Substitution of the C4 methylsulfanyl group in 7 with hydrogen or with electron rich aromatic compounds furnished corresponding 2-methylamino-3-nitro-4H-chromenes. Reduction of the nitro group with concomitant hydrolysis of the enamine moiety in 2-alkylamino-3-nitro-4H-chromenes or in 4-aryl-2-alkylamino-3-nitro-4H-chromenes with Zn, Ac2O and AcOH led to facile synthesis of lactones of ortho-tyrosine, four isomers of DOPA and the hybrid amino acid incorporating tryptophan and ortho-tyrosine units.

Palladium assisted transfer hydrogenation of cyclic α,β-unsaturated ketones by ammonium formate

Abstract α,β-Unsaturated ketones can be hydrogenated conveniently under catalytic transfer hydrogenation conditions using ammonium formate / Pd-C (10 %) in refluxing methanol.

Reduction of Aroyl Azides with Sodium Borohydride/Nickel (II) Chloride

Abstract Aroyl azides (cf. 1) generally are reduced to the corresponding amides 2 in very high yield and under mild conditions using the sodium borohydride / nickel (II) chloride system.

Characterization and phase transition study of a versatile molecular gel from a glucose-triazole-hydrogenated cardanol conjugate

The synthesis and gelation properties of a structurally simple, renewable-resource-based glucose-triazole-hydrogenated cardanol conjugate (GTHCC) are reported. The conjugation of hydrogenated cardanol and glucose was done using a triazole linker employing copper(I) mediated acetylene azide cycloaddition ‘click’ chemistry in the key step. The GTHCC was found to form four different classes of gels; namely, (i) hydrogel from aqueous-protic solvents, (ii) organogel from non-polar solvents, (iii) gel from vegetable oil and (iv) gel from petroleum oil. In a water–methanol (1 : 1) mixture, the conjugate acted as a stable thermoreversible supergelator, even at a very low gelator concentration of 0.03% w/v. Unlike glycoside-based gels derived from hydrogenated cardanol and glucose, the GTHCC is stable under acidic as well as basic conditions, owing to the covalent linkages in the tether. The intrinsic fluorescence of the hydrogel was found to be sensitive towards a gel–sol transition.

Nitroketene dithioacetal chemistry. Part 2: Synthesis of novel 4-(alkylsulfanyl)-2-[1-nitromethylidene]-1,3-dithioles from the dipotassium salt of 2-nitro-1,1-ethylenedithiol

Abstract The reaction of the dipotassium salt of 2-nitro-1,1-ethylenedithiol with long chain alkyl halides in acetonitrile medium furnished the novel heterocyclic, 4-(alkylsulfanyl)-2-[1-nitromethylidene]-1,3-dithioles.

Novel domino products from the reaction of phenyl vinyl ketone and its derivatives with cyclic ketones

Abstract Reaction of phenyl vinyl ketone with cyclopentanone under thermal conditions resulted in novel domino products, 1,5,9-triketones along with the expected 1,5-diketones. The 1,5,9-triketones were formed via a Michael–Michael-rearrangement pathway. On the other hand, reaction under basic conditions furnished a spiro[4.5]decanone, formed by domino pathways involving Michael–Michael-aldol condensation reactions. Microwave mediated reductive amination–cyclization of the 1,5,9-triketone furnished the perhydrocyclopenta[ij]quinolizine derivative.

Synthesis, in vitro and in silico antimalarial activity of 7-chloroquinoline and 4H-chromene conjugates.

A new series of chloroquinoline-4H-chromene conjugates incorporating piperizine or azipane tethers were synthesized and their anti-malarial activity were evaluated against two Plasmodium falciparum strains namely 3D7 chloroquine sensitive (CQS) and K1 chloroquine resistant (CQR). Chloroquine was used as the standard and also reference for comparison. The conjugates exhibit intense UV absorption with λmax located at 342 nm (log ε=4.0), 254 nm (log ε=4.2), 223 nm (log ε=4.4) which can be used to spectrometrically track the molecules even in trace amounts. Among all the synthetic compounds, two molecules namely 6-nitro and N-piperazine groups incorporated 7d and 6-chloro and N-azapane incorporated 15b chloroquinoline-4H-chromene conjugates showed significant anti-malarial activity against two strains (3D7 and K1) of P. falciparum. These values are lesser than the values of standard antimalarial compound. Molecular docking results suggested that these two compounds showing strong binding affinity with P. falciparum lactate dehydrogenase (PfLDH) and also they occupy the co-factor position which indicated that they could be the potent inhibitors for dreadful disease malaria and specifically attack the glycolytic pathway in parasite for energy production.

Synthesis and photochromic properties of benzofuran–phenanthrene and benzofuran–pyrene hybrids

Iron(III) chloride mediated condensation of phenanthrene-9,10-dione and pyrene-4,5-dione with cyclohexanone and its derivatives furnish benzofuran–phenanthrene and benzofuran–pyrene hybrids. Absorption and emission spectroscopic studies revealed the bathochromic effect of benzofuran annulation on the photophysical properties of the pyrene chromophore. Solvatochromic studies revealed that solvent polarity did not have a noticeable effect on the absorption or the emission spectra. While benzofuran annulation enhanced the quantum yield in most of the solvents, appending a methyl group, in fact, reduced the quantum yield. Thus, our studies delineated the synthesis and photophysical properties of selected PAHs with a furan ring.