Modular Synthesis of Polysubstituted Quinolin-3-amines by Oxidative Cyclization of 2-(2-Isocyanophenyl)acetonitriles with Organoboron Reagents

Synthesis of Polysubstituted Benzo[b][1,5]naphthyridine via Mn(III)-Mediated Domino Cascade Reactions of Cyclopropanols and 2-(2-Isocyanophenyl)acetonitriles

Domino cascade reactions, which can construct multiple bonds in one pot, are efficient methods to synthesize N-heterocycles and other useful skeletons. Herein, we report an expedient synthesis of polysubstituted benzo[b][1,5]naphthyridine via Mn(III)-mediated C-C bond cleavage of cyclopropanols. These reactions were initiated by addition of β-carbonyl radicals, generated from cyclopropyl alcohols in the presence of Mn(III), to 2-(2-isocyanophenyl)acetonitriles to give quinolin-3-amines, which went through intramolecular cyclizations and dehydrogenation to give the final products.

Rhodium-Catalyzed One-pot Chemoselective Insertion-Rearrangement-Cyclization of Azavinyl Carbenes with 2-Aminobenzyl Alcohols

Chemoselective insertion of in situ generated α-imino rhodium carbene onto the O-H bond of 2-aminobenzyl alcohols over the N-H bond followed by [1,3]-alky shift has been successfully accomplished for the synthesis of amine tethered ketone derivatives. The resultant product was further cyclized under acidic conditions to afford biologically important 3-aminoquinolines. Successful integration of chemoselective insertion-cum-rearrangement and cyclization in one pot offered access to various 3-aminoquinolines in a good yield. Conversion of 3-aminoquinolines into biological important motifs has also been demonstrated.

Manganese(III) Triacetate-Mediated Cross Coupling of Organoboron Compounds with Trichloroethylene (TCE): Synthesis of 1,1-Dichloroalkenes

Herein, we report an efficient method for the synthesis of 1,1-dichloroalkenes from organoboron compounds. This reaction proceeds in the presence of manganese(III) triacetate using trichloroethylene (TCE) as the vinylation reagent. This reaction can tolerate various types of organoboron compounds and various functional groups. The yields are moderate to good. Surprisingly, this transformation could even be achieved in the presence of manganese(II) acetate. Furthermore, this synthetic strategy could be applied to the synthesis of 1,1,2-trichloro-, 1-chloro-, and 2-chloroalkenes.

Visible Light-Induced Decomposition of Acyl Peroxides Using Isocyanides: Synthesis of Heteroarenes by Radical Cascade Cyclization

Visible light-mediated facile synthesis of heteroarenes, namely, isoquinolines, benzothiazoles, and quinazolines, is demonstrated by employing isocyanides and inexpensive acyl peroxides. It is shown for the first time that singlet-excited isocyanides decompose acyl peroxides into aryl/alkyl radicals. The latter attack isocyanides, yielding imidoyl radicals that subsequently cyclize to afford heteroarene products. The protocol involving radical cascade reactions obviates the requirement of any external photocatalyst, oxidant, additive, and base.

Oxidative Radical Transnitrilation of Arylboronic Acids with Trityl Isocyanide

We report a radical transnitrilation of arylboronic acids with trityl isocyanide in the presence of manganese(III) acetate. Many functional groups can be tolerated in this transformation, and a special positive effect of benzoic acid in this reaction has been observed.

Advances in free-radical alkylation and arylation with organoboronic acids

Organoboronic acids act as carbon-centered radical precursors that are widely utilized to construct diverse C-C bonds. This review summarizes the advances in this field. The content is divided into four parts according to the different categories of coupling partners with organoboronic acids. The reaction conditions as well as the mechanisms are demonstrated in each part.

Cyanomethylation of the Benzene Rings and Pyridine Rings via Direct Oxidative Cross-Dehydrogenative Coupling with Acetonitrile

A novel and efficient approach for the amine-directed dehydrogenative C(sp²)-C(sp³) coupling of arylamines with acetonitrile was reported by using FeCl₂ as the catalyst. Substituted anilines, aminopyridines, naphthylamines, and some nitrogen-containing heterocyclic arylamines react with inactive acetonitrile to form the corresponding arylacetonitriles in moderate to good yields. This protocol features nontoxic iron catalysis, efficient atom economy, nonprefunctionalized starting materials, good regioselectivity, and excellent compatibility of functional groups and aromatic rings, providing a novel, straightforward, and green approach toward arylacetonitriles.

Mn(iii)-Catalyzed cascade cyclization reaction of o-acyl aromatic isocyanides with boronic acids

A Mn(iii)-catalyzed cascade cyclization of o-acyl aromatic isocyanides with boronic acids was examined to give a series of 3-hydroxyindolenines in single-step. This cascade process involved a transmetalation/nucleophilic addition/intramolecular cyclization sequence.

Iodine-imine Synergistic Promoted Povarov-Type Multicomponent Reaction for the Synthesis of 2,2'-Biquinolines and Their Application to a Copper/Ligand Catalytic System

An efficient iodine-imine synergistic promoted Povarov-type multicomponent reaction was reported for the synthesis of a practical 2,2'-biquinoline scaffold. The tandem annulation has reconciled iodination, Kornblum oxidation, and Povarov aromatization, where the methyl group of the methyl azaarenes represents uniquely reactive input in the Povarov reaction. This method has broad substrate scope and mild conditions. Furthermore, these 2,2'-biquinoline derivatives had been directly used as bidentate ligands in metal-catalyzed reactions.