Copper-Catalyzed Tandem Nucleophilic Ring-Opening/Intramolecular Oxidative Amidation of N-Tosylaziridines and Hydrazones under Aerobic Conditions

Copper-catalyzed selective oxidation of hydrazones through C(sp3)-H functionalization

A simple and mild protocol for copper-catalyzed oxidation of hydrazones at the α-position has been reported. Various substrates are compatible, providing the corresponding products in moderate to good yields. This strategy provides an efficient and convenient solution for the synthesis of carbonyl hydrazone. A free radical pathway mechanism is suggested for the transformation.

DABCO-mediated [3+3] annulation of para-quinamines: access to functionalized 1,2,4-triazinone derivatives

A new [3+3]-annulation of p-quinamines and nitrile imines for affording 1,2,4-triazinone derivatives with excellent yields and excellent diastereoselectivity.

Ring-opening and cyclization of aziridines with aryl azides: metal-free synthesis of 6-(triflyloxy)quinolines

A metal-free synthesis of 6-(triflyloxy)quinolines has been developed via the ring-opening and cyclization of 2-aryl-1-tosylaziridines with 2-azidobenzaldehydes in the presence of TfOH.

Rhodium-catalyzed intermolecular [3+3] cycloaddition of vinyl aziridines with C,N-cyclic azomethine imines: stereospecific synthesis of chiral fused tricyclic 1,2,4-hexahydrotriazines

A new rhodium-catalyzed intermolecular [3+3] cycloaddition of vinylaziridines with C,N-cyclic azomethine imines has been described to construct enantioenriched 1,2,4-hexahydrotriazines.

Recent advances in copper-catalyzed C-H bond amidation

Copper catalysis has been known as a powerful tool for its ubiquitous application in organic synthesis. One of the fundamental utilities of copper catalysis is in the C–N bond formation by using carbon sources and nitrogen functional groups such as amides. In this review, the recent progress in the amidation reactions employing copper-catalyzed C–H amidation is summarized.

The Ti-BINOLate-catalyzed, enantioselective ring-opening of meso-aziridines with amines

The titanium-BINOLate-catalyzed, highly enantioselective ring-opening reaction of meso-aziridines has been developed which furnishes trans-1,2-diamines in typically good yields and excellent enantioselectivities. N-Aryl aziridines attached to a 5- or 6-membered carbocyclic ring are among the best substrates for this process providing the products in up to >99% ee. The chiral catalyst is easily prepared in situ from commercially available components and does not require any laborious ligand synthesis. Structural investigations into the catalyst composition reveal an oligomeric structure of the active Ti-complex.

Synthetic route to chiral indolines via ring-opening/C-N cyclization of activated 2-haloarylaziridines

A practical approach for the synthesis of 3-substituted indolines via regio- and stereoselective SN2-type ring-opening of 2-(2-halophenyl)-N-tosylaziridines with heteroatomic nucleophiles (O, N, and S) followed by palladium-catalyzed intramolecular C-N cyclization is reported in excellent yields (up to >99%) and enantiomeric excess (ee 99%).

Lewis acid-catalyzed [3 + 2]cyclo-addition of alkynes with N-tosyl-aziridines via carbon-carbon bond cleavage: synthesis of highly substituted 3-pyrrolines

A novel, efficient, and highly regioselective Lewis acid-catalyzed [3 + 2] cycloaddition of alkynes with azomethine ylides, which are easily obtained from N-tosylaziridines via C-C bond heterolysis at room temperature was developed. Moderate enantioselectivity (70% ee) can be achieved by the application of the commercially available chiral Pybox 7 as the ligand.

Synthetic route to chiral tetrahydroquinoxalines via ring-opening of activated aziridines

A highly regio- and stereoselective route for the synthesis of racemic and nonracemic tetrahydroquinoxalines via the S(N)2-type ring-opening of activated aziridines with 2-bromoanilines followed by the Pd-catalyzed intramolecular C-N bond formation is described.

Three-component synthesis of polysubstituted pyrroles from α-diazoketones, nitroalkenes, and amines

Polysubstituted pyrroles are regiospecifically synthesized via the copper-catalyzed three-component reaction of α-diazoketones, nitroalkenes, and amines under aerobic conditions. The cascade process involves an N-H insertion of carbene, a copper-catalyzed oxidative dehydrogenation of amine, and a [3 + 2] cycloaddition of azomethine ylide.

Lewis acid-catalyzed formal [3+2] cycloadditions of N-tosyl aziridines with electron-rich alkenes via selective carbon-carbon bond cleavage

A novel, mild, robust catalyst Y(OTf)(3) for C-C bond heterolysis of N-tosyl aziridines was developed and the resulting metallo-azomethine ylides may readily undergo [3+2] dipolar cycloaddition with an electron-rich olefin via a stepwise reaction pathway with high regio- and diastereoselectivity leading to substituted pyrrolidines.

Alumina-supported Cu(II), a versatile and recyclable catalyst for regioselective ring opening of aziridines and epoxides and subsequent cyclization to functionalized 1,4-benzoxazines and 1,4-benzodioxanes

An easily accessible catalyst, alumina-supported copper(II), efficiently catalyzes the ring opening of aziridines and epoxides followed by cyclization of the corresponding intermediate to produce a variety of functionalized 1,4-benzoxazines and 1,4-benzodioxanes, respectively, in one pot without any ligand in high yields. The ring cleavages of aziridines and epoxides are highly regioselective. The catalyst is inexpensive, non-air-sensitive, environmentally friendly, and recyclable. The function of the catalyst and the reaction pathway are postulated. This protocol is successfully utilized for the formation of three carbon-heteroatom bonds, namely, C-O, C-N, and C-S, in one pot.