TfOH-Catalyzed N-H Insertion of α-Substituted-α-Diazoesters with Anilines Provides Access to Unnatural α-Amino Esters

Rhodium(II)-Catalyzed N-H Insertions of Carbenes under Mechanochemical Conditions

Under mechanochemical conditions in a mixer mill, Rh2(OAc)4 catalyzes the reaction between aryldiazoesters and anilines to give α-amino esters. The process proceeds under mild conditions and is insensitive to air. It is solvent-free and scalable. A broad substrate scope, short reaction times, operational simplicity, and good functional group tolerance are additional salient features of this protocol.

General Ir-Catalyzed N-H Insertions of Diazomalonates into Aliphatic and Aromatic Amines

A general N-H insertion reactivity of acceptor-acceptor diazo malonate reagents is reported using [Ir(cod)Cl]2 as catalyst. A large range of amines, primary and secondary, aliphatic and aromatic, is possible. Mild temperatures, perfect substrate/reactant stoichiometry, and good functional group compatibility render the process particularly attractive for the (late-stage) functionalization of amines.

P(III)-Mediated Formal Reductive N-H Bond Insertion Reaction of Hydrazones to α-Keto Esters

A diazo-, metal-, and base-free multi-substituted hydrazone synthesis via a formal reductive N-H bond insertion reactions of hydrazones to α-keto esters has been developed. The protocol features a broad substrate scope and good functional group tolerance, providing N-H bond insertion products in moderate to excellent yields. Moreover, P(III)-mediated N-H functionalization of pharmaceutical containing hydrazone moiety was also successfully achieved.

Controllable Access to Diazo-functionalized 2-Methylene-2,3-dihydrofurans and Diazo-functionalized Furans from Enynones and Diazo Carbonyl Compounds

Using enynones and diazo carbonyl compounds as identical starting materials, methods for chemoselective and regioselective constructs of diazo-functionalized 2-methylene-2,3-dihydrofurans and diazo-functionalized trisubstituted furans have been established in a AgSbF6/DBU/DCE/0 °C system and a AgSbF6/DBU/Et2O·BF3/DCE/0 °C system, respectively. A Lewis acid and organic base cocontrolled reaction for the synthesis of diazo-functionalized trisubstituted furans is infrequent. For diazo-functionalized 2-methylene-2,3-dihydrofuran synthesis, the reaction possesses excellent diastereoselectivity and Z-selectivity. On the basis of Rh2(OAc)4-mediated unique decomposition of diazo-functionalized 2-methylene-2,3-dihydrofurans, an application to diastereoselective construction of a 5-methylene-4,7-dihydro-5H-furo[2,3-c]pyran frame has been achieved for the first time.

Synthesis of functionalized S-benzyl dithiocarbamates from diazo-compounds via multi-component reactions with carbon disulfide and secondary amines

Triflic acid promoted multi-component synthesis of functionalized S-benzyl dithiocarbamates from diazo compounds, carbon disulfide and secondary amines is reported. The reactions proceeded at room temperature and gave the desired dithiocarbamates in good yields. Wide-substrate scope and easy operation are the important features of this methodology.

TBAI-Catalyzed S-H and N-H Insertion Reactions of α-Diazoesters with Thiophenols and Amines under Metal-Free Conditions

Mild, convenient, and effective TBAI-catalyzed S-H and N-H insertion reactions of α-diazoesters with thiophenols and aromatic amines under metal-free conditions have been described, furnishing a straightforward and general platform for the synthesis of various thioethers and 2-amino-2-oxoacetates in moderate to excellent yields. Moreover, this strategy features simple operation, mild conditions, broad substrate scope, and easy scale-up.

TfOH-catalyzed regioselective N2-alkylation of indazoles with diazo compounds

Selective alkylation of indazoles is still a highly challenging topic in chemistry and the synthesis of important molecules. Herein, a novel highly selective N²-alkylation of indazoles with diazo compounds is described in the presence of TfOH. Unlike the traditional metal- and base-catalysed version, this protocol highlights the regioselectivity of alkylation of indazoles and a metal-free catalysis system, affording N²-alkylated products in good to excellent yields with high regioselectivity (N²/N¹ up to 100/0) and excellent functional group tolerance. Furthermore, a gram scale synthesis was conducted successfully to give rise to the corresponding products. Mechanistic studies through control experiments provide plausible mechanistic proposals.

A solvent controlled three-component reaction of diazo compounds for the synthesis of hydrazone compounds under Brønsted acid catalysis

A novel Brønsted acid catalyzed three-component reaction of diazo compounds has been achieved from α-diazo ester, N-aminophthalimide and a solvent.

Indium(iii)-catalyzed efficient synthesis of 3-arylhydrazonoindolin-2-ones and their fluorescent metal sensing studies

In(iii)-catalyzed strategy for the preparation of 3-arylhydrazonoindolin-2-ones from 3-diazoindoles is developed and used for Fe3+ and Hg2+ ion sensing.

TfOH-Catalyzed [4 + 1] Annulation of p-Quinone Methides with α-Aryl Diazoacetates: Straightforward Access to Highly Functionalized 2,3-Dihydrobenzofurans

We have developed a methodology for the greatly efficient construction of significant 2,3-dihydrobenzofuran scaffolds bearing a quaternary carbon center at the C2 position by means of [4 + 1] annulation reactions between p-quinone methides and α-aryl diazoacetates as C1 synthons through organocatalysis by readily accessible TfOH catalyst under mild and transition metal-free conditions. This metal-free protocol furnishes an operationally simple and swift process for the free assembly of diverse highly functionalized 2,3-dihydrobenzofurans and also features broad substrate scope, excellent functional group compatibility, and environmental friendliness. Mechanistic investigation suggested that the reaction undergoes a rapid cascade protonation/intermolecular Michael addition/intramolecular substitution process.