Bijivemula N. 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.

An efficient and green La(OTf)3 catalyzed Petasis borono–Mannich reaction for the synthesis of tertiary amines

A variety of tertiary amine derivatives have been prepared by a one-pot three-component Petasis borono–Mannich reaction of two different salicylaldehydes and 2-formylpyridine, substituted morpholine/piperidines and aryl boronic acids. These reactions were carried out under microwave irradiation using a catalytic amount of La(OTf)3 in a short reaction time. This procedure has the advantages of high conversions with excellent chemoselectivity.Graphical AbstractThe attractive features of this methodology are simple procedure, green reaction, reusability and high efficiency of the catalyst and easy workability.

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