Direct Amidation of 2′-Aminoacetophenones Using I2-TBHP: A Unimolecular Domino Approach toward Isatin and Iodoisatin

Electro-organic synthesis of isatins and hydrazones through C-N cross-coupling and C(sp2)-H/C(sp3)-H functionalization

An efficient and unique approach to synthesize isatin (indole-2,3-dione) from 2-aminoacetophenone under electrochemical conditions supported by I2-DMSO through C-N cross-coupling and C(sp2)-H/C(sp3)-H functionalization is presented. This synthetic method spans a wide range of substituted 2-aminoacetophenone substrates. The use of iodine as a promoter and shorter reaction times produced good to very good yields of isatin derivatives, which is a significant improvement over the reaction in a batch process. Further, hydrazones of isatin were synthesized by using hydrazine hydrate which produces electrochemically active molecules, namely isatin-hydrazones. The hydrazones of acetophenone were also obtained using the same reaction protocol. Additionally, the effect of increasing scan rate studied using cyclic voltammetry shows that the process followed a diffusion-controlled mechanism.

Evaluation of Anti-Neuroinflammatory Activity of Isatin Derivatives in Activated Microglia

Neuroinflammation plays a crucial role in the progression of Alzheimer's disease and other neurodegenerative disorders. Overactivated microglia cause neurotoxicity and prolong the inflammatory response in many neuropathologies. In this study, we have synthesised a series of isatin derivatives to evaluate their anti-neuroinflammatory potential using lipopolysaccharide activated microglia as a cell model. We explored four different substitutions of the isatin moiety by testing their anti-neuroinflammatory activity on BV2 microglia cells. Based on the low cytotoxicity and the activity in reducing the release of nitric oxide, pro-inflammatory interleukin 6 and tumour necrosis factor α by microglial cells, the N¹-alkylated compound 10 and the chlorinated 20 showed the best results at 25 µM. Taken together, the data suggest that 10 and 20 are promising lead compounds for developing new neuroprotective agents.

Bismuth(iii)-catalyzed regioselective alkylation of tetrahydroquinolines and indolines towards the synthesis of bioactive core-biaryl oxindoles and CYP19 inhibitors

Bismuth(iii)-catalyzed regioselective functionalization at the C-6 position of tetrahydroquinolines and the C-5 position of indolines has been demonstrated. For the first time, one pot symmetrical and unsymmetrical arylation of isatins with tetrahydroquinolines was accomplished giving a completely new product skeleton in good to excellent yields. Most importantly, this protocol leads to the formation of a highly strained quaternary carbon stereogenic center, which is a challenging task. Benzhydryl and 1-phenylethyl trichloroacetimidates have been used as the alkylating partners to functionalize the C-6 and C-5 positions of tetrahydroquinolines and indolines, respectively. The scope of the developed methodology has been extended for the synthesis of the bioactive CYP19-inhibitor and its analogue.

Synthesis of Epoxides from Alkyl Bromides and Alcohols with in Situ Generation of Dimethyl Sulfonium Ylide in DMSO Oxidations

Direct conversion of the readily available alkyl bromides and alcohols to value-added epoxides using dimethyl sulfoxide (DMSO) under mild reaction conditions has been developed. Benzyl and allyl bromides, and activated and unactivated alcohols all proceeded smoothly to give epoxides in high to excellent yield. Dimethyl sulfide, generated by DMSO oxidations, was in situ elaborated to form the substituted dimethyl sulfonium ylide species that participates in the Corey-Chaykovsky epoxidation in a domino and one-pot fashion, respectively.

Tritylium assisted iodine catalysis for the synthesis of unsymmetrical triarylmethanes

The combined Lewis acid catalytic system, generated from molecular iodine and tritylium tetrafluoroborate effectively catalyzed the Friedel-Crafts (FC) arylation of diarylmethyl sulfides providing an efficient access to various unsymmetrical triarylmethanes. The addition of tritylium and iodine created a more active catalytic system to promote the cleavage of sulfidic C-S bonds.

Iodine-Mediated Oxidative Rearrangement of α,β-Unsaturated Diaryl Ketones: A Facile Access to 1,2-Diaryl Diketones

A metal-free oxidative rearrangement was explored for the synthesis of 1,2-diaryl diketones by utilizing α,β-unsaturated diaryl ketones and I2/TBHP in good to high yields. The reaction proceeds via oxidative aryl migration, followed by C-C bond cleavage. A simple and high-yielding protocol was developed for the synthesis of a wide range of 1,2-diaryl diketones, which are the backbone for a variety of medicinally important molecules.

Copper-catalyzed oxidative amination of methanol to access quinazolines

A novel method for the copper-catalyzed oxidative amination of 2′-aminoarylketones with methanol as a C1 carbon source and ammonium acetate as an amine source to construct quinazolines was established in a one-pot manner.

NaI-mediated divergent synthesis of isatins and isoindigoes: a new protocol enabled by an oxidation relay strategy

A new approach for the synthesis of isatins and isoindigoes by an inexpensive and environmentally friendly NaI-mediated transformation is disclosed. The selectivity could be switched by simply varying the solvent, and isatins (using THF) and isoindigoes (using DMSO) could be obtained in moderate to excellent yields.

Copper-catalyzed domino sequences: a new route to pyrido-fused quinazolinones from 2'-haloacetophenones and 2-aminopyridines

A new pathway to access pyrido-fused quinazolinones via a Cu(OAc)2-catalyzed domino sequential transformation between 2'-haloacetophenones and 2-aminopyridines was demonstrated. The solvent and base exhibited a remarkable effect on the transformation, in which the combination of DMSO and NaOAc emerged as the best system. Cu(OAc)2·H2O was more active towards the reaction than numerous other catalysts. This methodology is new and would be complementary to previous protocols for the synthesis of pyrido-fused quinazolinones.

Indium-Catalyzed Annulation of o-Acylanilines with Alkoxyheteroarenes: Synthesis of Heteroaryl[b]quinolines and Subsequent Transformation to Cryptolepine Derivatives

We disclose herein the first synthetic method that is capable of offering heteroaryl[b]quinolines (HA[b]Qs) with structural diversity, which include tricyclic and tetracyclic structures with (benzo)thienyl, (benzo)furanyl, and indolyl rings. The target HA[b]Q is addressed by the annulation of o-acylanilines and MeO–heteroarenes with the aid of an indium Lewis acid that effectively works to make two different types of the N–C and C–C bonds in one batch. A series of indolo[3,2-b]quinolines prepared here can be subsequently transformed to structurally unprecedented cryptolepine derivatives. Mechanistic studies showed that the N–C bond formation is followed by the C–C bond formation. The indium-catalyzed annulation reaction thus starts with the nucleophilic attack of the NH₂ group of o-acylanilines to the MeO-connected carbon atom of the heteroaryl ring in an S_NAr fashion, and thereby the N–C bond is formed. The resulting intermediate then cyclizes to make the C–C bond through the nucleophilic attack of the heteroaryl-ring-based carbon atom to the carbonyl carbon atom, providing the HA[b]Q after aromatizing dehydration.

5-Bromo-1-(4-bromophenyl)isatin

In the title compound [systematic name: 5-bromo-1-(4-bromophenyl)-2,3-dihydro-1H-indole-2,3-dione], C14H7Br2NO2, all of the atoms except the C—H groups in the bromobenzene ring lie on a (010) crystallographic mirror plane, with the benzene ring completed by reflection. The dihedral angle between the ring systems is constrained to be 90° by symmetry. In the crystal, molecules are linked by weak C—H...Br interactions in the [001] direction and paired very weak C—H...O interactions to the same acceptor in the [100] direction, generating (010) sheets. Possible extremely weak π–π stacking occurs between the layers.

AgNO3-catalyzed direct C–H arylation of quinolines by oxidative decarboxylation of aromatic carboxylic acids

AgNO₃-catalyzed direct C–H arylation of quinolines by oxidative decarboxylation of aromatic carboxylic acids to afford aryl quinoline derivatives in moderate yields was described.

Copper-catalyzed aerobic oxidative intramolecular amidation of 2-aminophenylacetylenes: a domino process for the synthesis of isatin

A novel CuI-catalyzed oxidative amidation of 2-aminophenylacetylenes leading to the formation of isatins by using open air as an oxygen source has been developed. The reaction proceeded smoothly and provided a variety of isatin derivatives in good yields.

1-Benzyl-5-methylindoline-2,3-dione

The title compound, C16H13NO2, is an isatin (indole-2,3-dione) derivative. The isatin moiety is almost planar with an r.m.s. deviation of 0.022 Å, and its mean plane makes a dihedral angle of 74.19 (12)° with the benzyl ring. In the crystal, molecules are linked by C—H...O hydrogen bonds, formingC(6) chains propagating along thea-axis direction. The chains are linkedviaC—H...π interactions, forming slabs parallel to theabplane. Within the slabs there are weak π–π interactions present involving inversion-related isatin moieties.

Base catalysed intermolecular cyclisation of N-protected o-amino benzaldehyde/acetophenone with phosphorus/sulphur based allenes: facile synthesis of substituted quinolines

Base catalyzed reaction of N-Bz protected o-aminobenzaldehyde with allenylphosphonates affords O-phosphorylated quinolines via a route involving a thermal rearrangement.

Synthesis of fused oxazole-containing coumarin derivatives via oxidative cross coupling reaction using a combination of CuCl2 and TBHP

Various fused oxazoles containing coumarin derivatives were synthesized via an oxidative cross coupling reaction by employing 20 mol% CuCl₂ as the catalyst and TBHP as an oxidant.

Iodine-Mediated Efficient Synthesis of 2,3-Dihydro-Pyrazines

The synthesis of 2,3-dihydro-pyrazines has been developed by an efficient protocol of annulations of 1,2-diketones and ethylenediamine. A variety of 2,3-dihydro-pyrazines were prepared in high yields in the presence of a catalytic amount of iodine.

A, Bhanage BM. NIS-catalyzed oxidative cyclization of alcohols with amidines: a simple and efficient transition-metal free method for the synthesis of 1,3,5-triazines

A simple and efficient method for the synthesis of 1,3,5-triazines by NIS-catalyzed oxidative cyclization of alcohols with amidines has been developed. The reaction works smoothly under transition-metal and phosphine-free conditions.

K2S2O8-mediated metal-free direct C–H functionalization of quinones using arylboronic acids

Direct C–H functionalization of quinones with arylboronic acids is achieved using K₂S₂O₈ as the sole and efficient green catalytic system.

Transition-metal free synthesis of quinazolinones via tandem cyclization of 2-halobenzoic acids with amidines

A simple protocol for the synthesis of quinazoline-4(3H)-ones by tandem cyclization of 2-halobenzoic acids with amidines has been developed by using KOH as a base in DMSO at 120 °C.

Synthesis of isatins by the palladium-catalyzed intramolecular acylation of unactivated aryl C(sp2)–H bonds

Synthesis of isatins from formyl-N-arylformamides is achieved via PdCl₂-catalyzed intramolecular acylation.

Metal free synthesis of 2,4-diarylquinoline derivatives with enamides and imines

A simple and efficient way to construct quinoline derivatives using enamides and imines in metal free condition.