Facile synthesis of 2-bromoindoles by ligand-free CuI-catalyzed intramolecular cross-coupling of gem-dibromoolefins

Recent Advances in the Hofmann Rearrangement and Its Application to Natural Product Synthesis

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C-N bond formation reactions are the most important transformations in (bio)organic chemistry because of the widespread occurrence of amines in pharmaceuticals, natural products, and biologically active compounds. The Hofmann rearrangement is a well-known method used for the preparation of primary amines from amides. But, the traditional version of the Hofmann rearrangement often gave relatively poor yields due to over-oxidation or due to the poor solubility of some amides in aqueous base, and created an enormous amount of waste products. Developments over the last two decades, in particular, have focused on refining both of these factors affecting the reaction. This review covers both the description of recent advances (2000-2019) in the Hofmann rearrangements and its applications in the synthesis of heterocycles, natural products and complex molecules of biological interest. It is revealed that organo-catalytic systems especially hypervalent iodine-based catalysts have been developed for the green and environmentally friendly conversion of carboxamides to primary amines and carbamates.

Palladium-catalyzed tandem reaction of 2-chloroquinoline-3-carbaldehydes and isocyanides

A facile domino reaction of 2-chloroquinoline-3-carbaldehydes in one and two equivalents of isocyanide has been investigated. Three-component reactions of 2-chloroquinoline-3-carbaldehydes, isocyanides and amines are also described. In this Pd-catalyzed reaction under controlled conditions, three novel types of quinoline derivatives were formed via amidation, lactamization or carbamate formation along with the formation of C-C, C-N, and C-O bonds in a one-pot procedure.

Facile synthesis of 2-amino-3-bromoquinolines by palladium-catalyzed isocyanide insertion and cyclization of gem-dibromovinylanilines

A novel and efficient synthesis of 2-amino-3-bromoquinolines through palladium-catalyzed isocyanide insertion followed by intramolecular cyclization of gem-dibromovinylanilines was developed.

Syntheses of indolizinones from an intramolecular one-pot process of gem-dibromoolefins

A rare type of indolizinone is constructed from an Intramolecular one-pot process from gem-dibromoolefins.

Synthesis of 3-aryl-2-aminoquinolines: palladium-catalyzed cascade reactions of gem-dibromovinylanilines with tert-butyl isocyanide and arylboronic acids

A three-component cascade reaction involving gem-dibromovinylanilines, tert-butyl isocyanide and arylboronic acids for the efficient synthesis of 3-aryl-2-aminoquinolines has been developed.

Microwave irradiated synthesis of 2-bromo(chloro)indoles via intramolecular cyclization of 2-(gem-dibromo(chloro)vinyl)anilines in the presence of TBAF under metal-free conditions

2-Bromo(chloro)indoles were readily prepared through TBAF-promoted intramolecular cyclization of 2-(gem-dibromo(chloro)vinyl)anilines in excellent yields under metal-free and microwave irradiation conditions.

One-pot synthesis of benzofused heteroaryl azoles via tandem C-heteroatom coupling/C–H activation of azoles

The Cu(i) or Pd(ii)-catalyzed cross-couplings of gem-dihaloolefins with azoles via tandem C-heteroatom coupling/C–H activation for the preparation of benzofused heteroaryl azoles have been developed.