Nickel-Catalyzed Direct Sulfonylation of Styrenes and Unactivated Aliphatic Alkenes with Sulfonyl Chlorides.

A nickel-catalyzed direct sulfonylation of alkenes with sulfonyl chlorides has been developed using 1,10-phenanthroline-5,6-dione as the ligand. Unactivated alkenes and styrenes including 1,1-, 1,2-disubstituted alkenes can be subjected to the protocol, and a wide range of vinyl sulfones was obtained in high to excellent yields with good functional group compatibility. Notably, the process did not allow the desulfonylation of sulfonyl chloride or chlorosulfonylation of alkenes. Radical-trapping experiment supported that a sulfonyl free-radical was likely produced and triggered subsequent transformation in the process.

Metal-Free Selective Ortho-C-H Amidation of Hypervalent(III) Iodobezenes with N-Methoxy Amides under Mild Conditions.

A metal-free selective ortho-C-H amidation of aryl iodines(III) with the use of N-methoxy amides as aminating reagents under mild conditions is described here. In the protocol, excellent chemoselectivity and high regioselectivity were obtained. Notably, the iodine substituent rendered the amidation product suitable to be used for further elaboration.

Photoredox-Catalyzed Acyl Lactonization of Alkenes with Aldehydes: Synthesis of Acyl Lactones.

An acyl lactonization of alkenes with aldehydes under visible-light photoredox catalysis is described. With the protocol, a broad scope of alkenoic acids and aldehydes could be compatible and good functional group tolerance is obtained. A series of acyl lactones are obtained with isolated yields ranging from 50-95%. Mechanistic studies revealed that the transformation should proceed via a radical chain process.

Visible-Light Photoredox-Catalyzed Sulfonyl Lactonization of Alkenoic Acids with Sulfonyl Chlorides for Sulfonyl Lactone Synthesis.

A visible-light photoredox-catalyzed sulfonyl lactonization of unsaturated carboxylic acids with sulfonyl chlorides is described. This reaction features good functional group tolerance and a broad substrate scope, providing a simple and efficient protocol to access a wide range of sulfonyl lactones in high to excellent yields. Preliminary mechanistic investigations suggested that a free-radical pathway should be involved in the process.

Copper-Catalyzed Intermolecular C(sp2)-H Amination with Electrophilic O-Benzoyl Hydroxylamines.

A copper-catalyzed intermolecular electrophilic amination of benzamides with O-benzoyl hydroxylamines was achieved with the assistance of an 8-aminoquinolyl group. With this protocol, good compatibility was observed for a variety of aryl amides and heteroaryl amides, and excellent tolerance with various functional groups was achieved. Significantly, the monoaminated product was overwhelmingly delivered under the simple reaction conditions. Preliminary mechanistic investigations suggested that a radical pathway should be excluded and C-H activation be potentially the rate-determining step.

Copper(II)-Catalyzed Alkene Aminosulfonylation with Sodium Sulfinates For the Synthesis of Sulfonylated Pyrrolidones.

A copper-catalyzed direct aminosulfonylation of unactivated alkenes with sodium sulfinates for the efficient synthesis of sulfonylated pyrrolidones is described. This reaction features good functional group tolerance and wide substrate scope, providing an efficient and straightforward protocol to access this kind of pyrrolidones. Moreover, preliminary mechanistic investigations disclosed that a free-radical pathway might be invovled in the process.

Facile synthesis of unnatural ß-germyl-α-amino amides via Pd(ii)-catalyzed primary and secondary C(sp3)-H bond germylation.

Pd(ii)-Catalyzed direct C(sp3)-H germylation of α-AA derivatives with the assistance of a bidentate auxiliary for the efficient synthesis of ß-germyl-α-amino amides is reported. This protocol features good generality for primary and secondary C-H bonds of aliphatic amides. Mechanistic studies show that a crucial five-membered palladacycle intermediate may play a key role in this process.

Selective O-Cyclization of N-Methoxy Aryl Amides with CH2Br2 or 1,2-DCE via Palladium-Catalyzed C-H Activation.

A selective O-cyclization of N-methoxy aryl amides with CH2Br2 or 1,2-DCE (1,2-dichloroethane) via palladium-catalyzed C-H activation has been described. New C(sp3)-O and C(sp2)-C(sp3) bonds are forged simultaneously with the assistance of an N-methoxy amide group, and good functional group tolerance in substrates is observed. Preliminary mechanistic investigations show that the process may involve a five-membered palladacycle intermediate.

Site-Selective Alkenylation of δ-C(sp(3))-H Bonds with Alkynes via a Six-Membered Palladacycle.

Most chelation-assisted aliphatic C-H activation proceeds through a kinetically favored five-membered cyclometalated intermediate. Here, we report the first site-selective alkenylation of δ-C(sp(3))-H in the presence of more accessible γ-C(sp(3))-H bonds via a kinetically less favored six-membered palladacycle. A wide range of functional groups are tolerated, and the unique protocol can be applied to the synthesis of chiral piperidines. Moreover, mechanistic insights have been conducted to elucidate the origin of the unusual site-selectivity.

Catalyst-Controlled Amino- versus Oxy-Acetoxylation of Urea-Tethered Alkenes: Efficient Synthesis of Cyclic Ureas and Isoureas.

A catalyst-controlled vicinal amino- versus oxy-acetoxylation of alkenes with PhI(OAc)2 as the oxidant is described. The divergent synthesis of cyclic ureas and isoureas was achieved in good yields under mild conditions employing ambident urea nucleophiles. Both terminal and internal alkenes are compatible with this reaction protocol.

Pd(II)-Catalyzed Direct Sulfonylation of Unactivated C(sp(3))-H Bonds with Sodium Sulfinates.

A Pd(II)-catalyzed sulfonylation of unactivated C(sp(3))-H bonds with sodium arylsulfinates using an 8-aminoquinoline auxiliary is described. This reaction demonstrates excellent functional group tolerance with respect to both the caboxamide starting material and the sodium arylsulfinate coupling partner, affording a broad range of aryl alkyl sulfones. Moreover, the late-stage modification of complex molecules was achieved via this sulfonylation protocol.

Copper(II)-Catalyzed Direct Sulfonylation of C(sp(2))-H Bonds with Sodium Sulfinates.

A copper-catalyzed direct sulfonylation of C(sp(2))-H bonds with sodium sulfinates using a removable directing group is described. This reaction tolerates a wide range of functional groups, providing an efficient protocol for the synthesis of diverse aryl sulfones. Moreover, a series of 2,6-disubstituted benzamides could be synthesized via sequential C-H functionalization.

Copper-catalyzed synthesis of purine-fused polycyclics.

A novel protocol for a Cu-catalyzed direct C((sp(2)))-H activation/intramolecular amination reaction of 6-anilinopurine nucleosides has been developed. This approach provides a new access to a variety of multiheterocyclic compounds from purine compounds via Cu-catalyzed intramolecular N-H bond tautomerism which are endowed with fluorescence.

Palladium-catalyzed C-H bond functionalization of C6-arylpurines.

A highly regioselective Pd-catalyzed C(Ar)-H bond activation method was developed for the modification of purines (nucleosides) with different functional groups by using purine as a directing group. This approach provides a new access to a variety of functionalized purines (nucleosides) which are potentially of great importance in medicinal chemistry.

Pd(II)-catalyzed ortho arylation of 6-arylpurines with aryl iodides via purine-directed C-H activation: a new strategy for modification of 6-arylpurine derivatives.

Purine is utilized as a new directing group for the Pd-catalyzed monoarylation of 6-arylpurines with simple aryl iodides via C-H bond activation in good yields, providing a complementary tool for the modification of 6-arylpurines (nucleosides). Most importantly, purine can be used as a building block for nucleoside derivatives, and the use of purine as a directing group helps avoid additional synthetic steps.