Active sp3 C–H Bond Oxidation Initiated sp3–sp2 Consecutive C–H Functionalization of N-Arylglycine Amides: Construction of Isatins

Scalable Electrochemical Aerobic Oxygenation of Indoles to Isatins without Electron Transfer Mediators by Merging with an Oxygen Reduction Reaction

An approach to electrochemical oxygenation of indoles leading to isatins was developed by merging with a complementary cathode oxygen reduction reaction. The features of this green protocol include the use of molecular oxygen as the sole oxidant, it being free of an electron transfer mediator, and gram-scale preparation. Mechanistic studies suggested a radical process, and the two oxygen atoms in the isatins were both most likely from molecular oxygen. A detailed mechanism of the reaction utilizing density functional theory calculations was elucidated.

C-centered radical-initiated cyclization by directed C(sp3)–H oxidative functionalization

C(sp3)–H functionalization is attracting constant attention. This review emphasizes C-centered radicals initiated cyclization strategies by directed C(sp3)–H oxidative functionalization since 2012.

"On Water" Direct Organocatalytic Cyanoarylmethylation of Isatins for the Diastereoselective Synthesis of 3-Hydroxy-3-cyanomethyl Oxindoles

An "on water" organocatalytic cyanoarylmethylation of aryl acetonitrile to isatins is developed, giving products in high yields and up to excellent diastereoselectivities. A remarkable enhancement of reaction rates and diastereoselectivities by water was observed under mild conditions. Moreover, this approach provides a highly efficient and environmentally benign access to thermodynamic 3-hydroxy-3-cyanomethyl oxindoles.

One-step construction of molecular complexity by tert-butyl nitrite (TBN)-initiated cascade α,β-sp3 C-H bond difunctionalization and C-N bond cleavage

TBN-initiated cascade multifunctionalization of inert C-H and C-N bonds in N-arylazacycles has been realized under transition-metal free conditions, in which the synthetically useful oxime, N-NO and aldehyde functional groups were constructed in only one synthetic step.

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.

Radical Cation Salt-initiated Aerobic C-H Phosphorylation of N-Benzylanilines: Synthesis of α-Aminophosphonates

A radical cation salt-initiated phosphorylation of N-benzylanilines was realized through an aerobic oxidation of the sp3 C-H bond, providing a series of α-aminophosphonates in high yields. An investigation of the reaction scope revealed that this mild catalyst system is superior in good functional group tolerance and high reaction efficiency. The mechanistic study implied that the cleavage of the sp3 C-H bond was involved in the rate-determining step.

Iron promoted C3–H nitration of 2H-indazole: direct access to 3-nitro-2H-indazoles

An efficient C3–H functionalization of indazole has been demonstrated. Notably, this method involves chelation-free radical C–H nitration on 2H-indazole. The radical mechanism was confirmed by control experiments and quantum chemical calculations. The synthetic utility has been proven by the synthesis of bio-relevant benzimidazoindazoles via reductive cyclization.

Oxidation of active sp3C–H bonds initiated consecutive intermolecular/intramolecular cyclization between glycine derivatives ando-vinylphenols: construction of a polycyclic benzofuroquinoline skeleton

The construction of the polycyclic benzofuroquinoline skeleton was realized through a consecutive cyclization.

Metal-free photocatalyzed aerobic oxidative Csp3–H functionalization of glycine derivatives: one-step generation of quinoline-fused lactones

This reaction provides facile access to a series of valuable quinoline-fused lactones at room temperature under an air atmosphere.