Metal‐free directed ortho C–H iodination of biaryl‐2‐carbonitriles was developed. A series of 2′‐iodobiaryl‐2‐carbonitriles were synthesized from substituted biphenylcarbonitriles and naphthylbenzonitriles in reasonably good yields by using bis(pyridine)iodonium(I) tetrafluoroborate (IPy2BF4, Barluenga's reagent) and HBF4·OEt2. The biaryl‐2‐carbonitriles are useful precursors for the synthesis of benzocyclic ketones.

Chemical fusion of a naturally occurring pharmacophore (pterocarpan) with a fluorophore (acridone) by thermally induced cascade sigmatropic rearrangement leads to the formation of a structurally different class of DNA binding ligands. Competitive binding assay in the presence of a classical minor groove binder shows the possibility of DNA minor groove binding by the ligand 4a. High cell viability of the prepared molecular probes was of utility for nuclear staining as well as cell cycle analysis through fluorescence‐activated cell sorting (FACS).

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Herein, a transition metal-free approach for the access to 3,3’-disubstituted peroxyoxindole is disclosed which harnesses transient azaoxyallyl cation. The strategy is also applicable to the synthesis of structurally diverse α-peroxycarboxylic...

A number of hitherto unreported thieno [2,3-b]quinolin-4(9H)-ones 5a-f have been regioselectively synthesized from the corresponding 4-(prop-2-ynyloxy)quinolin-2(1H)-thiones 4a-f. The 4-(Prop-2-ynyloxy)quinolin-2(1H)-thiones 4a-f were prepared by the thionation of 4-(prop-2-ynyloxy)quinolin-2(1H)-ones 3a-f. The latter compounds were in turn prepared by the alkylation of 4-hydroxyquinolin-2(1H)-one (1).Various substituted furo[3,2-c]quinolin-4(5H)-ones, 2H-pyrano[3,2-c]quinolin-5(6H)-one derivatives are abundantly distributed in nature. 1,2 A number of synthesis for these heterocycles have been reported 3,4 which also includes our work. 5,6 We have also reported 7-9 regioselective synthesis of substituted furo[2,3-c]quinolin-4(5H)-ones and 2H-pyrano[2,3-c]quinolin-5(6H)-ones. However, so far there are no reports on the synthesis of corresponding thiophene or thiopyran annelated quinoline derivatives. This prompted us to undertake a study in this area. Here we report the results. 4-(Prop-2-ynyloxy)quinolin-2(1H)-one derivatives 3a-f were used as the starting material for this study. These were prepared by the reaction of 4-hydroxyquinolin-2(1H)-one derivative 1 (R = Me, Et, Ph) with propargylic bromides 2 (R 1 = H, Me) in refluxing acetone in the presence of anhydrous potassium carbonate (Scheme 1).Usually Claisen rearrangement of 4-allyloxy-or 4-propargyloxy quinoline is known to provide access to angularly fused heterocycles. Thionation of the quinolone carbonyl may change the mode of cyclization for the formation of new heterocyclic ring since sulfur is more nucleophilic than oxygen. With this in view, the 4-(prop-2-ynyloxy)quinolin-2(1H)-one derivatives were subjected to thionation with phosphorus pentasulfide in refluxing anhydrous benzene for 4-5 hours to give 4-(prop-2-ynyloxy)quinolin-2(1H)-thione derivatives as yellow crystalline solids, 4a-f in 70-80% yield (Scheme 2). Scheme 2Substrate 4a was subjected to thermal rearrangement by refluxing in chlorobenzene (132°C). The reaction was monitored by TLC and formation of a new component was indicated. It took almost 12 hours to complete the reaction to give 5a in 80% yield. The product 5a was characterized as 2,9-dimethylthieno[2,3-b]quinolin-4(9H)-one from its elemental analysis and spectroscopic data. 1 H NMR clearly exhibited a three proton singlet at d = 2.51 and mass spectrum showed a molecular ion peak at m/z = 229 (base peak). Encouraged by this result other substrates 4b-f were subjected to thermal rearrangement to give products 5b-f in 80-90% yield (Scheme 3).The formation of products 5a-f from 4a-f may be explained by considering an initial [1,3] sigmatropic shift of the propynyl group in 4a-f to give intermediates 8a-f. Enolization followed by cyclization may afford products 5a-f (pathway a, Scheme 4). Alternatively, the formation of products 5a, 5c, 5e may also be explained by the initial Scheme 1Downloaded by: East Carolina University. Copyrighted material.

Halogen incorporated arenes and heteroarenes are often used as useful intermediates as well as target products in organic synthesis. Often, CÀ H bond halogenation is attempted using transition metals (Pd, Cu, Au, Rh etc.). However, keeping the environmental concerns in mind, transition metal free protocols are more relevant and essential in recent times. In this context, improvised methods are widely being developed to evade transition metals. A great deal of work has been done on this topic in recent times and still going on. The intention of this review is to cover recent works on transition metal-free C(sp 2 )À H bond halogenations on arenes as well as heteroarenes.

A transition metal-free domino process has been developed, for the first time, to synthesize (E)-stilbenes, biaryl methanes and biaryl ethers from substituted a,b-unsaturated ketones, benzyl acetones and phenacyl ethers, respectively, in moderate to good yields at room temperature using diethyl aluminium chloride (Et 2 AlCl) as a Lewis acid.

Among the various other organic compounds, the compounds having heterocyclic core are extensively circulated in nature and are often crucial for life. The concerned heterocyle may or may not be aromatic. They often show a variety of physiological, industrial and also theoretical significance. Quinoline derivatives are very popular anti-biotics and benzopyran or chromenes is another important heterocyclic moiety found widely in naturally occurring plant products like fruits and vegetables. However, when chromene and quinoline are present in a molecule in fused form, a subclass of very important bio-active chromene-fused quinoline heterocycles is formed. This review covers recent reports on transition metalfree synthesis of chromeno-quinoline derivatives in short and hassle-free reaction protocols.