By employing cheap and biodegradable natural deep eutectic solvent as the catalyst and reaction media, the selective selenocyanation of activated alkynes via an intermolecular H-bonding activation pathway has been achieved, which allows for the efficient construction of various Z-vinyl selenolates.
The development of a mild and general method for C(sp3)−H functionalization of cyclic amines has been an ongoing challenge. In this work, we describe the copper‐catalyzed enantioselective C(sp3)−H alkynylation of unactivated cyclic 2‐iodo‐benzamide under photo‐irradiation by intramolecular 1,5‐hydrogen atom transfer (HAT). The employment of a new bisoxazoline diphenylamine ligand, in conjunction with 1,1′‐bi‐2‐naphthol, which significantly improved the reduction potential of the copper complex, was the key to success of this chemistry. Mechanistic and computational studies supported that the new copper complex served the dual role as a photoredox and coupling catalyst, the reaction went through a radical process, and the intramolecular 1,5‐HAT process was involved in the rate‐limiting step. Apart from the broad substrate scope including unprecedented benzocyclic amines, this method also showed excellent diastereoselectivity in 2‐monosubstituted cyclic amines via substrate control.
A new set of stereochemically diverse phosphino-oxazoline ligands derived from simple L-amino acids and 2-(diphenylphosphaneyl)benzoic acid were developed. Those mono anionic tridentated N,N,P-ligands promote the Cu-catalyzed enantioselective radical coupling of terminal alkynes with a broad range of benzylic halides including benzo-fused cyclic α-halides and α-silyl benzyl halides in high yield and excellent enantioselectivity under mild reaction conditions. With multi distinct sites for structural modification, a diverse pool of chiral N,N,P-ligands is readily accessed, allowing for rapid optimization of the ligand structure for a specific substrate. Notably, the enantioselective alkynlylation of benzylic halides bonds in benzo-cyclic molecules has also been realized for the first time.
In recent years, visible-light-mediated copper photocatalysis have emerged as an attractive strategy for the diverse constructions of basic bonds in an ecologically benign and cost-effective fashion. The intense activity and increasing work of these areas stimulated the exploit of the distinctive properties of copper photocatalysis and the rapid development and expansion of their applications. In this review, we focus on introducing a series of significant achievements in copper complexes as standalone photocatalysis in organic reactions to make an attempt to exhibit their potential capabilities and high flexibilities in synthetic chemistry.
The development of a mild and general method for C(sp 3 )À H functionalization of cyclic amines has been an ongoing challenge. In this work, we describe the copper-catalyzed enantioselective C(sp 3 )À H alkynylation of unactivated cyclic 2-iodo-benzamide under photo-irradiation by intramolecular 1,5-hydrogen atom transfer (HAT). The employment of a new bisoxazoline diphenylamine ligand, in conjunction with 1,1'-bi-2-naphthol, which significantly improved the reduction potential of the copper complex, was the key to success of this chemistry. Mechanistic and computational studies supported that the new copper complex served the dual role as a photoredox and coupling catalyst, the reaction went through a radical process, and the intramolecular 1,5-HAT process was involved in the rate-limiting step. Apart from the broad substrate scope including unprecedented benzocyclic amines, this method also showed excellent diastereoselectivity in 2-monosubstituted cyclic amines via substrate control.
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