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

Chitin and Silk Fibroin Biopolymers Modified by Oxone: Efficient Heterogeneous Catalysts for Knoevenagel Reaction

New materials from silk fibroin (FS-Ox) and chitin (CT-Ox) functionalized with Oxone® salt were developed for application in the synthesis of Knoevenagel adducts. The experiments were performed using benzaldehyde derivatives, malononitrile, and a mixture of water and ethanol as green solvents. The efficiency of conventional and microwave irradiation as heating sources for this reaction was also investigated. When the reactions were performed for 60 min under optimized conditions with conventional heating, twelve Knoevenagel adducts 2a–l were obtained, with good yields for both catalysts (CT-Ox 60–98% and FS-Ox 71–98%). When microwave irradiation was used, the reaction periods were reduced twelvefold, with the same Knoevenagel adducts with good CT-Ox (39–99%) and FS-Ox (35–99%) yields obtained in most cases. The reuse of these materials as catalysts in successive reactions was also evaluated, and CT-Ox FS-Ox were successfully used for 4 and 2 cycles, respectively. The results presented prove the efficiency of the CT-OxFS-Ox catalyst as a promising low-cost and reusable material with suitable catalytic properties to be applied in the aldol condensation reaction in a sustainable way.

Promiscuous Lipase-Catalyzed Knoevenagel-Phospha-Michael Reaction for the Synthesis of Antimicrobial β-Phosphono Malonates

An enzymatic route for phosphorous–carbon bond formation was developed by discovering new promiscuous activity of lipase. We reported a new metal-free biocatalytic method for the synthesis of pharmacologically relevant β-phosphonomalononitriles via a lipase-catalyzed one-pot Knoevenagel–phospha–Michael reaction. We carefully analyzed the best conditions for the given reaction: the type of enzyme, temperature, and type of solvent. A series of target compounds was synthesized, with yields ranging from 43% to 93% by enzymatic reaction with Candida cylindracea (CcL) lipase as recyclable and, a few times, reusable catalyst. The advantages of this protocol are excellent yields, mild reaction conditions, low costs, and sustainability. The applicability of the same catalyst in the synthesis of β-phosphononitriles is also described. Further, the obtained compounds were validated as new potential antimicrobial agents with characteristic E. coli bacterial strains. The pivotal role of such a group of phosphonate derivatives on inhibitory activity against selected pathogenic E. coli strains was revealed. The observed results are especially important in the case of the increasing resistance of bacteria to various drugs and antibiotics. The impact of the β-phosphono malonate chemical structure on antimicrobial activity was demonstrated. The crucial role of the substituents attached to the aromatic ring on the inhibitory action against selected pathogenic E. coli strains was revealed. Among tested compounds, four β-phosphonate derivatives showed an antimicrobial activity profile similar to that obtained with currently used antibiotics such as ciprofloxacin, bleomycin, and cloxacillin. In addition, the obtained compounds constitute a convenient platform for further chemical functionalization, allowing for a convenient change in their biological activity profile. It should also be noted that the cost of the compounds obtained is low, which may be an attractive alternative to the currently used antimicrobial agents. The observed results are especially important because of the increasing resistance of bacteria to various drugs and antibiotics.

One-Pot Multicomponent Synthesis and Cytotoxic Evaluation of Novel 7-Substituted-5-(1H-Indol-3-yl)Tetrazolo[1,5-a] Pyrimidine-6-Carbonitrile

A series of novel 7-substituted-5-(1H-indol-3-yl)tetrazolo[1,5-a]pyrimidine-6-carbonitrile was synthesized via a one-pot, three-multicomponent reaction of appropriate aldehydes, 1H-tetrazole-5-amine and 3-cyanoacetyl indole in catalytic triethylamine. The cytotoxic activity of the new synthesized tetrazolopyrimidine-6-carbonitrile compounds was investigated against HCT-116, MCF-7, MDA-MB-231, A549 human cancer cell lines and one human healthy normal cell line (RPE-1) using the MTT cytotoxicity assay. Compounds 4h, 4b, 4c, 4i and 4a showed potent anticancer activities against human colon cancer. Additionally, all the compounds showed potent anticancer activities on human lung cancer.

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.

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

A highly efficient and green protocol has been developed for the synthesis of novel tertiary α-amino phosphonates via a catalyst-free multi-component Kabachnik–Fields reaction under ultrasound irradiation.

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

Aldehydic carbonyl groups are eco-friendly and efficiently hydrophosphonylated by diethylphosphite using the basic ionic liquid, choline hydroxide.