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An efficient cascade annulation protocol was established to access substituted 2-hydroxybenzocarbazoles from alkynylcyclohexadienones and substituted 2-aminophenols under gold catalysis. In this transformation a new C-C, two C-N bonds were formed sequentially and moderate to excellent yields of 2-hydroxybenzocarbazole derivatives were obtained selectively via Meyer-Schuster rearrangement in one-pot.

An exclusive synthesis of benzo-oxazine, benzo-oxazepine, and benzo-oxazocine from aryl propanal and 2-(hydroxyamino)phenyl alcohol under metal-free conditions is described. O atom transfer and formation of new C═O, C-N, and C-O bonds occur at room temperature to form six-, seven-, and eight-membered heterocycles under one-pot reaction conditions without using an external oxidant and base. The photophysical properties are studied using ultraviolet-visible absorption and photoluminescence. The mechanistic elucidation is well supported by control experiment and literature precedents.

A novel chemoselective [3 + 2] annulation reaction of easily accessible ketoxime acetate with 2-aryl-3-ethoxycarbonyl pyrroline-4,5-dione has been developed for the synthesis of unknown pyrrolo[2,3

One‐pot sulfenylation/selenylation reaction have been developed to access 3‐sulfenyl/selenylimidazo[1,5‐a]quinolines from 2‐methylquinolines, aliphatic amines/amino acids and dichalcogenides. This developed method gives direct access to 3‐chalcogenylimidazo[1,5‐a]quinolines in moderate to good yields with good functional group tolerance from readily available starting materials. Moreover, this protocol can avoid the prior synthesis of fused imidazoles as starting materials for the synthesis of 3‐chalcogenylimidazo[1,5‐a]quinolines. Further, we have shown synthetic utility of 3‐sulfenylimidazo[1,5‐a]quinolines with m‐CPBA to afford corresponding sulfones in good to excellent yields.

A cationic Pd(IV)-catalyzed arylative hydroxylation-Micheal addition of allenyl-tethered cyclohexadienones was developed. This relay reaction could afford highly diastereoselective various functionalized arylative 1,4-dioxane cis-bicyclic structural units with good to high yields. The striking features revealed from these studies is the necessity of Selectfluor and the oxidative hydroxylation originating from water initiated by F–Pd(IV) catalysis. A plausible mechanism was also proposed for this variant observation.

An effective and expeditious approach for the construction of biologically important 5-guanidino-1,2,4-thiadiazole and 1,2,4-triazolo[1,5-a]pyridine derivatives has been developed. This new protocol involves the phenyliodine(III) diacetate [PhI(OAc)2]-mediated oxidative cyclization of thioureas/2-aminopyridines and imidates via N–S and N–N bond formation at ambient temperature. This method furnishes the versatile 5-guanidino-1,2,4-thiadiazoles and 1,2,4-triazolo[1,5-a]pyridines in a scalable manner with high efficiency and excellent regioselectivity.

A highly regio- and stereoselective method was developed for the preparation of

An efficient 2-furyl gold–carbene promoted synthetic method was developed for the formation of dihydroquinazolinones from enynones by dual insertion of anthranilamides. In this organic transformation a new C–O and two C–N bond formations occurred and dihydroquinazolinones were obtained with a quaternary centre in moderate to very good yields in one-pot synthesis.

A series of eight novel ferrocene–oxime ether benzyl 1H-1,2,3 triazole hybrids 5a–h were designed and synthesized by employing Cu(I) catalyzed azide–alkyne [3+2] cycloaddition (CuAAC) between ferrocenecarboxaldehyde oxime O-propargyl ether and benzyl azides. The alkyne, ferrocenecarboxaldehyde oxime O-propargyl ether 3, was synthesized by converting ferrocenecarboxaldehyde 1 into ferrocenecarboxaldehyde oxime 2 with subsequent O-propargylation. All the ferrocenyl triazole derivatives are remarkably stable crystalline solids and were obtained in good yields. All the products were well characterized by means of various analytical and spectroscopic techniques. The electrochemical behavior of the synthesized ferrocene–oxime ether benzyl triazole hybrids was investigated. Further, the structure of one of the triazoles 5a was unambiguously established by means of single-crystal X-ray diffraction study. All the triazole compounds have been screened for in vitro antimicrobial activity against two Gram-positive (Bacillus subtilis and Staphylococcus aureus) and two Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae), and one fungal (Candida albicans) microorganism. All the ferrocene–oxime ether benzyl 1H-1,2,3 triazole hybrids have shown moderate to good inhibitory activity against most of the tested bacterial and fungal strains in comparison with standard drugs.

An efficient method was developed for the synthesis of substituted aryl-fused pyrazolooxazepines from ortho-O-propargyl aryl pyrazoles by gold catalysis. In this organic transformation a new C-N bond was formed regioselectively via 7-exo-dig cyclization. Moderate to good yields of aryl-fused pyrazolooxazepine derivatives were obtained with significant molecular complexity in one-pot.

An asymmetric Mannich reaction has been developed to generate chiral β-amino esters in good yields with excellent enantiomeric excesses (ee, up to 99%) using a chiral bifunctional thiourea catalyst derived from (R,R)-cyclohexyldiamine. This is the first report on the addition of 3-indolinone-2-carboxylates to N-Boc-benzaldimines generated in situ from α-amidosulfones, which proceeds under mild conditions.

A copper-mediated domino condensation reaction of readily accessible oxime acetates with ninhydrin is reported to afford pyrrolo[2,1-a]isoindolediones via new C-C & C-N bond formations. A wide range of oxime acetates were shown to generally participate in the reaction to produce the condensed products in excellent yields. The necessary control experiments were performed and the mechanism is proposed to involve sequentially the formation of iminium radical via Cu-mediated N-O bond cleavage of oxime acetates, addition of the radical to ninhydrin and rearrangement via ring expansion.

A facile method for the construction of double bond between 3-ylidene oxindoles and α-azido ketones has been successfully accomplished with a mild base. This method features azido reduction with concomitant double bond formation to provide the new class of bioactive enamino-2-oxindoles. These new compounds were screened for their in vitro cytotoxic potential on selected human cancer cell lines such as colon, lung, breast, and cervical cancer cells. Among them, representative compounds 3a, 3h, 3k, 3p, 3w and 3x showed notable cytotoxicity profile with IC50 values ranging from 1.40 ± 0.10 to 28.7 ± 0.36 µM. Compound 3k displayed most potent cytotoxicity against lung cancer (NCI-H460) cells with an IC50 value of 1.40 ± 0.10 µM. 3k also arrested the G2/M phase of the cell cycle and induced distinctive apoptotic features on lung cancer cells. The apoptosis induction is supported by various cellular assays such as AO/EB, DAPI, and DCFDA staining studies including clonogenic assay. Extent of apoptosis was also analyzed by Annexin binding and JC-1 staining. Moreover, this method is amenable for the generation of a library of new class of stable bioactive enamino-2-oxindoles.

A novel, one-pot reaction for the synthesis of 3,4-dihydroisoquinolin-2(1H)-one derivatives is developed via a base-mediated three-component reaction of ninhydrin, aniline and acetylenic esters. This diastereoselective reaction takes place in methanol at 70 °C under transition-metal-free conditions, and direct construction of the C–N and C–C bonds is readily achieved via tandem cyclization. These cyclic frameworks are resourceful small molecular keys to many natural products.

An unusual and unexpected synthesis of 3-(2-(arylamino)thiazol-4-yl)-2H-chromen-2-ones has been observed by the reaction of ethyl 2-(chloromethyl)-2-hydroxy-2H-chromene-3-carboxylate with various arylthioureas in ethanol under mild reaction conditions with excellent yields. The ambiguity in the structure of the obtained products has been solved by recording its single-crystal X-ray analysis. This protocol has been found to be a novel approach for the preparation of title compounds via benzopyran ring opening. A systematic plausible mechanism has been proposed for the formation of the product. Also, an efficient one-pot three-component method has been demonstrated for the formation of title compounds starting from salicylaldehyde.

A novel method has been developed for the synthesis of highly substituted enecarbamates and trisubstituted alkenes from arylhydrazine-1,2-dicarboxylates and 1,2-disubstituted alkynes through a sequential C-C and C-N bond formation. It is entirely a new strategy to produce enecarbamates in a highly regio- and stereoselective manner.

A mild domino rearrangement strategy for the direct access to substituted quinoline‐4‐carboxamides has been developed. This copper‐catalyzed coupling reaction of O‐acyl oximes with isatins in the presence of molecular oxygen as the sole oxidizing agent proceeds through a ring expansion of the isatins through cleavage of the two CN bonds