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A novel and regioselective ammonium iodide mediated CS bond formation protocol involving flavones and sulfonyl chlorides to generate different ArS-substituted flavone derivatives in high yields was developed. Different from existing metal-free CS bond formation protocols with the use of PPh3 or I2 as the catalyst, this method provides an alternative way of constructing CS bonds through the use of NH4I as a catalyst, which makes it highly valuable for the efficient synthesis of thioether compounds.

A novel and highly regioselective ammonium iodide-induced nonradical sulfenylation method for the construction of a C–S bond was developed via C–H functionalization. With DMSO or R1SO2NHNH2 as a sulfenylating agent, MeS- and R1S-substituted flavone derivatives were obtained in good yields. This method enriches current C–S bond formation chemistry, making it a highly valuable and practical method in pharmaceutical industry.

Depending on the amount of base used, this method yields either benzofurans (III) and (V) with high diastereoselectivity or benzopyrans (VI) and (VII).

An efficient and practical method for effecting a tandem C-H alkenylation/C-O cyclization has been achieved via the C-H functionalization of flavone derivatives. The synthetic utility of the one-pot sequence was demonstrated by obtaining convenient access to coumarin-annelated benzopyrans. The reaction scope for the transformation was found to be fairly broad, affording good yields of a wide range of flavone- or coumarin-fused benzopyran motifs, which are privileged structures in many biologically active compounds.

Flavones have antioxidant, anti-proliferative, anti-tumor, anti-microbial, estrogenic, acetyl cholinesterase, anti-inflammatory activities and are also used in cancer, cardiovascular disease, neurodegenerative disorders, etc. Also, flavonoids are found to have an effect on several mammalian enzymes like protein kinases that regulate multiple cell signaling pathways and alterations in multiple cellular signaling pathways are frequently found in many diseases. Flavones have been an indispensable anchor for the development of new therapeutic agents. The majority of metabolic diseases are speculated to originate from oxidative stress, and it is therefore significant that recent studies have shown the positive effect of flavones on diseases related to oxidative stress. Due to the wide range of biological activities of flavones, their structure-activity relationships have generated interest among medicinal chemists. The outstanding development of flavones derivatives in diverse diseases in very short span of time proves its magnitude for medicinal chemistry research. The present review gives detail about the structural requirement of flavone derivatives for various pharmacological activities. This information may provide an opportunity to scientists of medicinal chemistry discipline to design selective, optimize as well as poly-functional flavone derivatives for the treatment of multi-factorial diseases.

A palladium-catalyzed oxidative arylation of chromones was examined. A regioselective 2-arylation of chromone was carried out via a double C–H activation process. The procedure provided an expedient approach for the preparation of flavone derivatives.

All newly synthesized benzofurans (I), furochromones (II), and flavones (III) as well as selected intermediates are evaluated for their anticonvulsant activity using both scPTZ and MES tests.

In the course of our search for new antitumor agents in breast cancer, novel amino-substituted flavone derivatives were synthesized and examined for antitumor activities. Among them, 5,4‘-diaminoflavone and some of its congeners showed remarkable antiproliferative activity against the estrogen receptor (ER)-positive and estrogen-responsive human breast cancer cell line MCF-7. The activity was observed irrespective of the presence or absence of estrogen. The 5-aminoflavone derivatives (5-AFs) are not classical anti-estrogens because they did not compete with [3H]estradiol to bind the estrogen receptor. Moreover, 5-AFs showed antitumor activity highly selective to the ER-positive breast cancer cell line, and they showed no effects against the ER-negative human cancer cell lines HeLa S3, WiDr, and MDA-MB-453. Although the mechanism of their selective antitumor activity to ER-positive breast cancer cells is unclear, 5-AFs are expected to be a new type of antitumor agents in breast cancer.

A series of 2'-, 3'-, 4'- and 6-substituted flavone derivatives was synthesized and their in vitro effects on rat liver microsomal NADPH-dependent lipid peroxidation (LP) levels were determined. Retinoic acid, at 10(-4) M concentration, decreased the LP level by about 34%. A significant decrease in male liver microsomal LP level was noted for the compounds 3d, 1a, 3b and 4b at a concentration of 10(-4) M (100%, 95%, 75% and 62%, respectively).

Various 3-haloflavones were prepared by the reaction of the corresponding flavone derivatives with iodobenzene diacetate and trimethylsilyl halide under mild reaction conditions. The iodobenzene diacetate could be replaced by the polymer supported iodobenzene diacetate without the decreasing activity. See Reference [1a], [1b], [1c], [1d], [1e], [1f], [1g].

Various 3-halo flavones were prepared by reaction of the corresponding flavone derivatives with R4NBr/PhI(OAc)2 system under mild reaction conditions.

Several new flavones/flavanones and 5'-substituted-2'-hydroxy chalcones have been synthesised through Claisen Schmidt condensation. 5-Chloromethyl-2- hydroxy acetophenone 1 on condensation with various aromatic aldehydes yields chalcones 2a and 2b, which on cyclisation in presence of SeO 2 give corresponding flavones 2c and 2d respectively. Compound 3 is obtained from 1 by reacting with o-toluidine. Further condensation of 3 with different aromatic aldehydes gives the corresponding chalcone/flavone derivatives 3a-e. The synthesised flavonoid derivatives are evaluated for their antiinflammatory activity on carrageenan induced paw edema in rats and in vitro antibacterial activity. The results have been encouraging.