BroÌ·nsted Acid-Catalyzed [5+1] and [4+1] Annulation of Cyclic Anhydrides with o-Alkynylanilines to Construct Fused-N-Heterocycles.

An unprecedented p-TsOH and MsOH-catalyzed construction of valuable isoindolo/pyrido/pyrrolo-quinolinediones and isoindolo-indolones is demonstrated through annulation reactions of cyclic anhydrides or o-formylbenzoates with o-alkynylanilines. The metal-free BroÌ·nsted acid-mediated new [5+1] and [4+1] fused-cyclization is an operationally simple, highly regioselective, atom economical, high yielding, sustainable, and catalytically efficient approach.

K2CO3-Catalyzed Dual C-C-Coupled Cyclization to 3-Amino-4-benzoylbiphenyls and In Situ I2-Catalyzed C-N Bond Forming Annulation: A Metal-Free Synthesis of Arylacridones.

Unprecedented metal-free cyclization catalysis reactions are developed in a highly regioselective fashion to synthesize 3-amino-4-benzoyl biphenyls and arylacridones with high atom economy. Catalytic K2CO3 is utilized as the only reagent for the unusual rapid dual C-C-coupled cyclization between ß-keto enamines and cinnamaldehydes to furnish the functionalized biphenyls. Its C(sp2)-H functionalized C-N bond-forming cyclization was performed in situ using molecular I2 as a catalyst to furnish valuable arylacridones. Plausible mechanisms for the new cyclization reactions are predicted by conducting various control experiments and ESI-MS analyses.

NHC-Mediated Stetter-Aldol and Imino-Stetter-Aldol Domino Cyclization to Naphthalen-1(2H)-ones and Isoquinolines.

N-Heterocyclic carbene-catalyzed tandem Stetter-aldol reaction of phthalaldehyde and α,ß-unsaturated ketimines has been developed to afford functionalized naphthalen-1(2H)-one derivatives as the formal [4+2] annulation product. Interestingly, the reaction of aldimines led to the formation of isoquinoline derivatives instead of the expected indanone derivatives as a [4+1] annulation product.

Metal-Free Indole-Phenacyl Bromide Cyclization: A Regioselective Synthesis of 3,5-Diarylcarbazoles.

A metal-free, simultaneous triple C-C coupling cyclization reaction between phenacyl bromides and indoles is discovered in a highly regioselective fashion to furnish 3,5-diarylcarbazoles. DMAP is utilized as the only reagent for the unusual and rapid cyclization reaction to furnish all new carbazole compounds through installation of a great diversity of substituents. A plausible radical mechanism for the new reaction is predicted by conducting various control experiments, competitive reactions, furoindole formation, and ESI-MS analyses of the ongoing cyclization reaction.

Iodine-Catalyzed Functionalization of Primary Aliphatic Amines to Oxazoles, 1,4-Oxazines, and Oxazinones.

Unprecedented I2-catalyzed α,α-C(sp3)-H, decarboxylative α-C(sp3)-H, lactonized α-C(sp3)-H, and α,ß-C(sp3)-H functionalized 5- and 6-annulation as well as α-C(sp3)-H activated 6-lactonization of primary aliphatic amines are devised under aerobic conditions. The metal-free sustainable strategy was employed for the diverse construction of valuable five-and six-membered polycyclic N,O-heteroaromatics such as oxazoles, 1,4-oxazines, and oxazin-2-one with a rapid reaction rate and high yield. The viability of this mild nonmetallic catalysis is successfully verified through syntheses of labile chiral heterocyclic analogues. In contrast to the common practice, this method is not limited to use of prefunctionalized amines, directing groups (DGs) and/or transient DGs, metal catalysts, and traditional oxidants. The possible mechanistic pathway of the annulation reaction is investigated by control experiments and ESI-MS data collected for a reaction mixture of the ongoing reaction. The synthesized new compounds are potent organic nanobuilding blocks to achieve valuable organic nanomaterials of different sizes, shapes, and dimensions, which are under investigation for the discovery of high-tech devices of innovative organic nanoelectronics and photophysical properties.

3-Amino-1-methyl-1 H-pyridin-2-one-Directed PdII Catalysis: C(sp3)-H Activated Diverse Arylation Reaction.

A new bidentate directing group, 3-amino-1-methyl-1 H-pyridin-2-one, is introduced to achieve a powerful PdII metallacycle for selective γ-C(sp3)-H activation and arylation of aromatic and aliphatic carboxylic acid derivatives. The versatility of the directing group is validated for remote arylation of ß-C(sp3)-H, ß-C(sp2)-H, and γ-C(sp2)-H to achieve therapeutically important 2-pyridone analogues and arylated acid synthons. The traceless removal of the directing group to retrieve the directing element and carboxylic acids makes this method more interesting.

Composition-dependent nanoelectronics of amido-phenazines: non-volatile RRAM and WORM memory devices.

A metal-free three component cyclization reaction with amidation is devised for direct synthesis of DFT-designed amido-phenazine derivative bearing noncovalent gluing interactions to fabricate organic nanomaterials. Composition-dependent organic nanoelectronics for nonvolatile memory devices are discovered using mixed phenazine-stearic acid (SA) nanomaterials. We discovered simultaneous two different types of nonmagnetic and non-moisture sensitive switching resistance properties of fabricated devices utilizing mixed organic nanomaterials: (a) sample-1(8:SA = 1:3) is initially off, turning on at a threshold, but it does not turn off again with the application of any voltage, and (b) sample-2 (8:SA = 3:1) is initially off, turning on at a sharp threshold and off again by reversing the polarity. No negative differential resistance is observed in either type. These samples have different device implementations: sample-1 is attractive for write-once-read-many-times memory devices, such as novel non-editable database, archival memory, electronic voting, radio frequency identification, sample-2 is useful for resistive-switching random access memory application.

Multifold C-C Coupling and Unorthodox Cyclization Catalysis for Selective Synthesis of Indolotriarylmethanes, Indolocarbazoles, and Their Analogues: A Control Experiment Study.

The selective construction of medicinally and synthetically important indole-based unsymmetrical triarylmethanes using indoles and aldehydes is challenging because the significant nucleophilicity of indole leads to C-C coupling with an azafulvene intermediate to build up the alternative bis(indolyl)methane products, which may be useful synthons. A new, straightforward, ligand-free CuII catalytic strategy for easy syntheses of unsymmetrical indolotriarylmethanes and new bisindolylbenzoyl analogues is established through the dual C-C coupling of an assembly of three reaction partners comprising aldehydes, indoles, and arylboronic acids. More importantly, this approach is exploited for multifold C-C coupling cyclization reactions with C-C cleavage using symmetrical bisindolylbenzoylmethanes in the presence of an organic base and aerial molecular oxygen as a stoichiometric oxidant. In contrast to the formation of a simple cyclocondensation product indolocarbazole, it undergoes unprecedented selective pseudo-four-component tandem oxidative cyclization with fragmentation from a 1,3-dicarbonyl compound to produce valuable fused 5,7-dihydroindolo[2,3-b]carbazoles through the functionalization of two indole C(sp2)-H and one C(sp3)-H bond of the active methylene residue. For a better understanding of the new reactions, we have studied various competition experiments and ESI-MS and 3D Mid-IR-ATR spectral analyses of the ongoing reactions. The predicted DFT transition state model is also in agreement with the experimental results.