Peddiahgari Vasu Govardhana Reddy

Rapid synthesis of alkylaminophenols via the Petasis borono–Mannich reaction using protonated trititanate nanotubes as robust solid–acid catalysts

An effective and rapid synthesis of alkylaminophenols using the one-pot three-component Petasis borono–Mannich (PBM) reaction was carried out using protonated trititanate (H2Ti3O7) nanotubes as a heterogeneous solid–acid catalyst. Complimentary to earlier reports, Ti–O based materials with various morphologies, such as fine particles, nanospheres, nanorods, and tubes were explored for their catalytic activity in the PBM reaction. The XRD pattern revealed the layered trititanate structure of nanotubes and nanorods; anatase and biphasic anatase–rutile structures for fine particles and nanospheres, respectively. Surface area analysis and NH3-TPD adsorption results confirmed the larger surface area and high concentration of Bronsted and Lewis acid sites present in H2Ti3O7 nanotubes. The catalytic efficiency for the PBM reaction is observed in the following order: H2Ti3O7 nanotubes > H2Ti3O7 nanorods > TiO2 nanospheres > TiO2 fine particles. The remarkable catalytic performance of H2Ti3O7 nanotubes was ascribed to a sufficient amount of hydroxy groups and high concentration of Bronsted and Lewis acid sites on the tubular surface, which are essential for adsorption and catalytic reactions. The recyclability of H2Ti3O7 catalyst is another emphasis for the proposed methodology. For the first time, we reported novel alkylaminophenols bearing 2-(pyrimidin-2-yl)-2,5-diazabicyclo[2.2.1]-heptane.

PEPPSI-SONO-SP2: a new highly efficient ligand-free catalyst system for the synthesis of tri-substituted triazine derivatives via Suzuki–Miyaura and Sonogashira coupling reactions under a green approach

The pyridine containing decidedly resourceful Pd–N-heterocyclic carbene complex, PEPPSI-SONO-SP2, is being used as a first class catalyst for Suzuki–Miyaura and Sonogashira cross coupling reactions. The catalyst showed a great performance in the consecutive reactions of 4-(4′,6′-dichloro-1,3,5-triazin-2-yl)morpholine with various boronic acids and terminal acetylenes under mild and green conditions (ethanol:water) even in the absence of a blanket of inert atmosphere. Significantly, all the synthesized compounds were found to be new and the catalyst is used for the first time in these reactions. The findings suggest that 0.1 mol% of catalyst is sufficient, recyclable and can be reused for six cycles.

Synthesis of New 4,5-Dihydro-1-methyl-[1,2,4]triazolo[4,3-a]quinolin-7-amine–Derived Ureas and Their Anticancer Activity

Abstract A new series of 1,2,4-triazolo[4,3-a]-quinoline derivatives were designed and synthesized to meet the structural requirements essential for anticancer activity. N-1-(5-Methylisoxazol-4-yl/4-fluoro-2,3-dihydro-1H-inden-1-yl/aryl)-N’-3-(4,5-dihydro-1-methyl-[1,2,4]triazolo[4,3-a]quinolin-7-yl) urea derivatives were accomplished in good yields by the reaction of 4,5-dihydro-1-methyl-[1,2,4]triazolo[4,3-a]quinolin-7-amine with 3-(3-chloro-5-fluoro-2-methoxyphenyl)-5-methyl-isoxazole-4-carboxylic acid, 4-fluoro-2,3-dihydro-1H-indene-1-carboxylic acid, and various simple aromatic carboxylic acids in the presence of diphenyl phosphoryl azide (DPPA). All the newly synthesized title compounds were characterized by elemental and spectral data. Furthermore, anticancer activity was screened for the title compounds (12a–j) in vitro against human neuroblastoma cell lines (SK N SH) and human colon carcinoma cell lines (COLO 205) by using the MTT cell viability method. A few of them (12a and 12b) possess significant cytotoxicity, and some other compounds 12d-f and 12j displayed moderate cytotoxicity against both cell lines. GRAPHICAL ABSTRACT

Cu(OTf)2 loaded protonated trititanate nanotubes catalyzed reaction: a facile method for the synthesis of furo[2,3-b]quinoxalines

An efficient method is developed for the synthesis of furo[2,3-b]quinoxalines using novel Cu(OTf)2 loaded protonated trititanate nanotube catalysts via A3-coupling followed by 5-endo-dig cyclization from o-phenylenediamines, ethylglyoxalate and phenylacetylenes. This method is beneficial and advantageous as it facilitates high yield in conventional heating and a short reaction time besides offering reusable heterogeneous catalysts. These catalysts can be recovered by centrifugation and their activity remain largely unchanged for five successive runs. On the other side, these catalysts are prepared using simple hydrothermal and wet-impregnation methods and are characterized using XRD, HR-TEM and N2-adsorption–desorption techniques.