Reddi Mohan Naidu Kalla

Synthesis of 2-amino-3-cyano-4H-chromen-4-ylphosphonates and their anticancer properties.

A series of 2-amino-3-cyano-4H-chromen-4-ylphosphonates have been synthesized by reacting substituted salicylaldehydes, malononitrile, and dialkylphosphites using a catalytic amount of dibutylamine as an organocatalyst employing Knoevenagel, Pinner, and phospha-Michael reactions simultaneously in ethanol. This protocol is an environmentally friendly procedure and gives high yields of the desired compounds (85-96%). In addition, no extraction or chromatography steps are needed to obtain the desired products. The compounds are tested against the viability of adenocarcinomic human alveolar basal epithelial (A549) and human epidermoid cancer (KB) cell lines using an MTT assay. Among these, diethyl 2-amino-3-cyano-4H-chromen-4-ylphosphonate and diethyl 2-amino-6-bromo-3-cyano-4H-chromen-4-ylphosphonate showed promising anticancer activity against the two tested cell lines.

Tungstosulfonic acid as an efficient solid acid catalyst for acylal synthesis for the protection of the aldehydic carbonyl group

Tungstosulfonic acid (TSA) has been found to be an efficient solid acid catalyst for the protection of aldehydic carbonyl groups by geminal diacetate (acylal) formation following the nucleophilic addition of acetic anhydride under neat conditions as well as in a solvent. The TSA catalyst is fully characterized by infrared spectroscopy, wide-angle X-ray scattering analysis, and scanning electron microscopy with energy dispersive X-ray spectroscopy. The deprotection of acylals to corresponding aldehydes has also been investigated under the similar conditions. The catalyst can be reused seven times without a significant loss of activity. In addition, no chromatographic separations are needed to obtain the desired products. This method is a green approach for the chemoselective protection of aldehydes in the presence of ketones.

Efficient, Solvent-Free, Multicomponent Method for Organic-Base-Catalyzed Synthesis of β-Phosphonomalonates

An efficient, one-pot, di-n-butylamine-catalyzed, three-component synthesis of β-phosphonomalonates has been developed. A wide range of substrates, including aromatic and fused aromatic aldehydes, were condensed with enolizable C-H activated compounds and dialkylphosphites to give the desired products in excellent yields. This method provides an eco-friendly alternative approach to rapid construction of a diversity-oriented library of β-phosphonomalonates.

Phospho sulfonic acid: an efficient and recyclable solid acid catalyst for the solvent-free synthesis of α-hydroxyphosphonates and their anticancer properties

As a means of developing biologically active compounds, a series of α-hydroxyphosphonates, ArC(OH)PO(OR)2 (Ar = 5-G-2-OHPh; R = Me, Et, iPr, Bu; G = H, Br, Cl, NO2), have been synthesized by reacting diversely substituted salicylaldehydes with dialkyl phosphites by employing the Pudovik reaction in the presence of phospho sulfonic acid under neat conditions. The cytotoxicity of the compounds was tested in two human cancer cell lines by using MTT assay. Compounds bearing R = Et; G = Cl, R = Bu; G = Cl, and R = Et; G = NO2 showed good anticancer activity.

Catalyst-free ultrasonic-promoted multicomponent synthesis of tertiary α-amino phosphonates

A highly efficient and green protocol has been developed for the synthesis of a new class of tertiary α-amino phosphonates (TAPs) via the Kabachnik–Fields reactions of substituted salicylaldehydes and 2-hydroxy naphthaldehyde, di-n-butylamine, and di-or tri-alkylphosphites in water under ultrasound irradiation as well as under conventional conditions. These multi-component reactions were performed at room temperature without using any catalysts in water. The TAPs were obtained in higher yields (84% to 94%) within shorter reaction times (6 min to 35 min) than those of conventional reactions after simple workup and purification procedures.

Highly efficient green synthesis of α-hydroxyphosphonates using a recyclable choline hydroxide catalyst

Choline hydroxide has been found to be an efficient basic ionic liquid catalyst for the synthesis of α-hydroxyphosphonates. Hydrophosphonylation of aldehydes was performed via the nucleophilic addition of diethylphosphite to aldehydic carbonyl compounds, in the presence of choline hydroxide under neat as well as solvent conditions. A wide array of substrates, including aromatic, fused aromatic, and heterocyclic aldehydes, were efficiently converted to their corresponding products in good yields. This protocol provides an alternative method for the straightforward synthesis of α-hydroxyphosphonates in high yields.

Synthesis of Bis(indolyl)methanes Using Hyper-Cross-Linked Polyaromatic Spheres Decorated with Bromomethyl Groups as Efficient and Recyclable Catalysts

Highly uniform and hyper-cross-linked polyphenanthrene and polypyrene microspheres were synthesized by Friedel–Crafts bromomethylation of phenanthrene (Phn) and pyrene (Py) in the presence of zinc bromide as a catalyst, followed by self-polymerization of bromomethylated Phn and Py. The resultant 3-D carbon microspheres consisting of micro-, meso-, and macropores bear peripheral unreacted bromomethyl groups, which are directly utilized as catalysts to efficiently promote the electrophilic substitution reaction of indoles with aldehydes to yield a variety of bis(indolyl)methanes. The important features of this catalysis are easy catalyst synthesis, high product yields, environmental benignity, short reaction time, broad substrate scope, use of nontoxic solvents, and recyclability.