Metal-Free Radical Azidoarylation of Alkenes: Rapid Access to Oxindoles by Cascade CN and CC Bond-Forming Reactions

Palladium-catalyzed picolinamide-directed coupling of C(sp(2))-H and C(sp(2))-H: a straightforward approach to quinolinone and pyridone scaffolds

An unprecedented palladium-catalyzed picolinamide-directed coupling of C(sp(2))-H and C(sp(2))-H has been developed with exclusive formation of the six-membered ring heterocyclics - quinolinone and pyridone. The method employs cyclic hypervalent iodine as oxidant and features good functional-group tolerance. Another advantage of this reaction is that sequential C-H/C-H and C-H/N-H coupling could be achieved.

Sunlight-Driven Decarboxylative Alkynylation of α-Keto Acids with Bromoacetylenes by Hypervalent Iodine Reagent Catalysis: A Facile Approach to Ynones

A novel and practical decarboxylative alkynylation of α-keto acids with bromoacetylenes is catalyzed by hypervalent iodine(III) reagents when irradiation by sunlight at room temperature. The product ynones are generated in good yields. Experiments show that results obtained with blue light (λ=450-455 nm) are comparable to those obtained when using sunlight. Mechanistic studies demonstrate that the sunlight-driven decarboxylation undergoes a radical process.

Stereoselective synthesis of highly functionalized indanes and dibenzocycloheptadienes through complex radical cascade reactions

Two highly stereoselective radical-mediated syntheses of densely functionalized indanes and dibenzocycloheptadienes from ortho-vinyl- and ortho-vinylaryl-substituted N-(arylsulfonyl)-acrylamides, respectively, are presented here. The chemoselective addition of in situ generated radicals (X(·)) onto the styrene moieties triggers an unprecedented reaction cascade, resulting in the formation of one new C-X bond and two new C-C bonds, a formal 1,4-aryl migration, and the extrusion of SO2 to generate an amidyl radical intermediate. This intermediate, upon H abstraction, leads to the observed 5- and 7-membered ring carbocyclic products, respectively, in a highly efficient manner.

Oxidative Heterocycle Formation Using Hypervalent Iodine(III) Reagents

Hypervalent iodine(III) reagents have been widely exploited in a diverse array of synthetic transformations. This chapter focuses on the general application of hypervalent iodine(III) reagents in the de novo synthesis and in the late stage functionalization of heterocyclic compounds.

Regioselective annulation of nitrosopyridine with alkynes: straightforward synthesis of N-oxide-imidazopyridines

We have developed intermolecular annulation of 2-nitrosopyridine derivatives with substituted alkynes for the regioselective access of N-oxide-imidazo[1,2-a]pyridines.

Synthesis of 3,3-disubstituted oxindoles by organoselenium-induced radical cyclizations of N-arylacrylamides

A simple and practical approach to oxindole derivatives

Metal-free direct cyanoisopropylation/arylation of N-arylacrylamides or N-alkyl-N-(arylsulfonyl)acrylamides with AIBN: a simple and mild approach to cyano-containing oxindoles

A general, highly efficient approach to cyano-containing oxindoles is presented that is achieved by a metal-free direct cyanoisopropylation/arylation ofN-arylacrylamides orN-alkyl-N-(arylsulfonyl)acrylamides with AIBN.

The development of carbene-stabilized N–O radical coupling strategy in metal-free regioselective C–H azidation of quinoline N-oxides

The key regioselective issue of quinoline N-oxide azidation was resolved via the oxidative cross-coupling of carbene-stabilized N–O radicals and TMSN₃. Compared with the reported azidations, the present metal-free procedure is convenient and regioselective under mild conditions, and could be scaled up to gram-synthesis.

Fe-promoted radical cyanomethylation/arylation of arylacrylamides to access oxindoles via cleavage of the sp3 C–H of acetonitrile and the sp2 C–H of the phenyl group

Radical cyanomethylation/arylation of arylacrylamides to access oxindoles with acetonitrile as a radical precursor is described, involving dual C–H bond functionalization.

Mn(iii)-mediated phosphonation–azidation of alkenes: a facile synthesis of β-azidophosphonates

A new and general method for the synthesis of β-azidophosphonates has been achieved through Mn(OAc)₃-mediated radical oxidative phosphonation–azidation of alkenes.

Metal-free TBAI-catalyzed arylsulfonylation of activated alkenes with sulfonylhydrazides

An efficient approach to isoquinoline-1,3(2H,4H)-dione derivatives through metal-free oxidative arylsulfonylation of α,β-unsaturated imides with sulfonylhydrazides is developed.

Di-tert-butyl peroxide (DTBP) promoted dehydrogenative coupling: an expedient and metal-free synthesis of oxindoles via intramolecular C(sp2)–H and C(sp3)–H bond activation

An efficient di-tert-butyl peroxide (DTBP) promoted synthesis of oxindole has been developed. This methodology involves C(sp³)–H and C(sp²)–H bond activation under metal-free conditions.

Morita-Baylis-Hillman reaction of acrylamide with isatin derivatives

The Morita–Baylis–Hillman reaction of acrylamide, as an activated alkene, has seen little development due to its low reactivity. We have developed the reaction using isatin derivatives with acrylamide, DABCO as a promoter and phenol as an additive in acetonitrile. The corresponding aza version with acrylate and acrylonitrile has also been developed resulting in high product yields.

Pd(0)-Catalyzed radical aryldifluoromethylation of activated alkenes

A Pd(0)-catalyzed intramolecular aryldifluoromethylation of activated alkenes under mild reaction conditions has been developed. This reaction provides a new method for construction of a variety of difluoromethylated oxindoles. Mechanistic investigations indicate that a difluoromethyl radical, which was triggered by Pd(0), initiated the cascade sequence through an addition to the alkene.