Direct difunctionalization of activated alkynes via domino oxidative benzylation/1,4-aryl migration/decarboxylation reactions under metal-free conditions

The oxidative difunctionalization of aryl alkynoatesviaa tandem oxidative benzylation/1,4-aryl migration/decarboxylation to trisubstituted alkenes was developed under metal-free conditions.

Transition metal-free cross-dehydrogenative coupling acylation of coumarins by the K2S2O8/Aliquat 336 catalytic system: a versatile strategy towards 4-aroylcoumarin derivatives

A new and efficient transition metal-free oxidative cross-dehydrogenative coupling (CDC) reaction is described for the preparation of 4-aroylcoumarin derivatives.

Transition metal-free synthesis of α-ketoamides from arylmethyl ketones and alkylphosphoramides

Synthesis of α-ketoamides from arylmethyl ketones and hexalkylphosphoramides using TBAI as the catalyst and TBHP as the oxidant.

Synthesis of esters via sp3 C–H functionalisation

This review describes various methods for the synthesis of eleven classes of esters involving sp³ C–H functionalisation.

Benzylation of heterocyclic N-oxides via direct oxidative cross-dehydrogenative coupling with toluene derivatives

A novel cross-dehydrogenative coupling (CDC) of heterocyclic N-oxides with toluene derivatives has been disclosed.

A metal free domino synthesis of 3-aroylindoles via two sp³ C-H activation

A metal free synthesis of 3-aroylindole involving two sp(3) C-H activation has been achieved starting from o-alkynyl-N,N-dialkylamines using catalyst TBAI and oxidant TBHP.

A NCS mediated oxidative C-H bond functionalization: direct esterification between a C(sp(3))-H bond and carboxylic acids

A transition metal free oxidative C-H bond functionalization/esterification of α-alkoxy alkanes with acids is described in this report. This method is effectively mediated by NCS instead of traditional oxidants, like TBHP or its derivatives, and directly generates the esterification products in moderate to high yield under mild conditions. This tranformation constitutes a practical and general approach toward various α-acyloxy ethers with broad substrate generality; alkyl-, aryl-, alkenyl- and alkynyl-carboxylic acids are all well tolerated.

Cross-dehydrogenative coupling for the intermolecular C-O bond formation

The present review summarizes primary publications on the cross-dehydrogenative C-O coupling, with special emphasis on the studies published after 2000. The starting compound, which donates a carbon atom for the formation of a new C-O bond, is called the CH-reagent or the C-reagent, and the compound, an oxygen atom of which is involved in the new bond, is called the OH-reagent or the O-reagent. Alcohols and carboxylic acids are most commonly used as O-reagents; hydroxylamine derivatives, hydroperoxides, and sulfonic acids are employed less often. The cross-dehydrogenative C-O coupling reactions are carried out using different C-reagents, such as compounds containing directing functional groups (amide, heteroaromatic, oxime, and so on) and compounds with activated C-H bonds (aldehydes, alcohols, ketones, ethers, amines, amides, compounds containing the benzyl, allyl, or propargyl moiety). An analysis of the published data showed that the principles at the basis of a particular cross-dehydrogenative C-O coupling reaction are dictated mainly by the nature of the C-reagent. Hence, in the present review the data are classified according to the structures of C-reagents, and, in the second place, according to the type of oxidative systems. Besides the typical cross-dehydrogenative coupling reactions of CH- and OH-reagents, closely related C-H activation processes involving intermolecular C-O bond formation are discussed: acyloxylation reactions with ArI(O2CR)2 reagents and generation of O-reagents in situ from C-reagents (methylarenes, aldehydes, etc.).

Guanidinium iodide-catalyzed oxidative α-nitroalkylation of β-ketoamides

Oxidative nitroalkylation of β-ketoamides and nitroalkanes, mediated by hypoiodide generated from tert-butyl hydrogen peroxide and a catalytic amount of guanidinium iodide, afforded the corresponding α-nitroalkyl-β-ketoamides in up to 97% yield.

Direct oxidative coupling of thiols and benzylic ethers via C(sp3)–H activation and C–O cleavage to lead thioesters

An unprecedented protocol for the synthesis of thioesters via C–H thioesterification and C–O cleavage was developed. This CDC protocol was found convenient and easy-to-handle involving the use of DTBP as the only green oxidant.

Copper(i)-promoted cycloalkylation–peroxidation of unactivated alkenes via sp3C–H functionalisation

A copper-promoted cycloalkylation–peroxidation strategy has been developedviaa three-component reaction involving cycloalkanes,tert-butyl hydroperoxide and internal conjugated alkene.

Oxidative acylation of sulfoximines with methylarenes as an acyl donor

An efficient direct oxidative acylation of sulfoximines with methylarenes as an acyl donor was finally achieved.

Copper(ii)-promoted direct conversion of methylarenes into aromatic oximes

A simple and efficient catalytic system for direct conversion of methylarenes into aromatic oximes has been developed, with Cu(OAc)₂ as catalyst, NHPI (N-hydroxyphthalimide) as additive, tert-butyl nitrite (TBN) as both the nitrogen source and the oxidant. The process proceeds under mild conditions, tolerates a wide range of substrates, affording the corresponding aromatic oximes in 63–86% yields.

Selective formation of C–N and CN bonds via C(sp3)–H activation of isochroman in the presence of DTBP

An organocatalytic approach for the synthesis of isochroman derivatives via direct C(sp³)–H bond and N–H bond coupling is described. The C–N (amine or amide) and CN (imidate) products can be selectively achieved by controlling the amount of oxidants.

Oxidant controlled regioselective mono- and di-functionalization reactions of coumarins

C-3 alkylation of coumarins has been accomplished using cycloalkanes/alkylbenzenes and Fe^III/DTBP while C-4 cycloalkylation–C-3 peroxidation has been achieved using AcOH/TBHP.

Copper-catalyzed oxidative esterification of unactivated C(sp3)–H bonds with carboxylic acids via cross dehydrogenative coupling

An effective copper-catalyzed esterification of unactivated (non-benzylic and allylic) C(sp³)–H bonds of hydrocarbons with Selectfluor as an oxidant has been developed.

Utilization of methylarenes as versatile building blocks in organic synthesis

This review attempts to describe the latest developments in the utilisation of methylarenes adopting C–H functionalization strategies and covers all the developments until March 2015.

Benzylic ethers as arylcarboxy surrogates in substrate directed ortho C–H functionalisation catalysed by copper

A copper catalysed o-benzoxylation of 2-arylpyridines has been accomplished using benzylic ethers as the alternative arylcarboxy sources (ArCOO–).

Tuning radical reactivity using iodine in oxidative C(sp3)–H/C(sp)–H cross-coupling: an easy way toward the synthesis of furans and indolizines

Molecular iodine was found to be an effective redox catalyst for the oxidative cross-coupling of carbonyl compounds with terminal alkynes.

C1-Benzyl and benzoyl isoquinoline synthesis through direct oxidative cross-dehydrogenative coupling with methyl arenes

An oxidative cross-dehydrogenative coupling of isoquinolines with methyl arenes has been developed, yielding structurally diverse C₁-benzyl and -benzoyl isoquinolines selectively. The direct use of readily available methyl arenes as coupling partners avoids unproductive steps for preactivating functional group installation, and is thereby attractive.

Copper-catalyzed oxidative coupling of acids with alkanes involving dehydrogenation: facile access to allylic esters and alkylalkenes

A new copper-catalyzed oxidative coupling of acids with alkanes for selective synthesis of allylic esters and alkylalkenes is described.

TBHP/TFA mediated oxidative cross-dehydrogenative coupling of N-heterocycles with aldehydes

A metal-free oxidative cross-dehydrogenative coupling of N-heterocycles with diverse aldehydes has been established in the presence of TBHP/TFA.