Triazenolysis of alkenes as an aza version of ozonolysis.

Alkenes are broadly used in synthetic applications, thanks to their abundance and versatility. Ozonolysis is one of the most canonical transformations that converts alkenes into molecules bearing carbon-oxygen motifs via C=C bond cleavage. Despite its extensive use in both industrial and laboratory settings, the aza version-cleavage of alkenes to form carbon-nitrogen bonds-remains elusive.

Stable 2-Azaallyl Salts as a Bridge between 2-Azirines and Densely Functionalized 2-Pyrroles.

An efficient protocol for the synthesis of stable 2-azaallyl anion salts by the reaction of alkyl 2-bromo-2-azirine-2-carboxylates with trimethylsilyl cyanide/BuNF has been developed. The domino reaction proceeds in four steps via the cleavage of the azirine C-C bond to provide the tetrabutylammonium salts of stereochemically pure 2-azaallyl anions having U-configuration relative to the cyano groups. The anions with an -substituted aryl group or styryl group exist as a mixture of two geometrical isomers across the N2-C3 bond.

Triethylamine-Promoted Oxidative Cyclodimerization of 2-Azirine-2-carboxylates to Pyrimidine-4,6-dicarboxylates: Experimental and DFT Study.

An unprecedented oxidative cyclodimerization reaction of 2-azirine-2-carboxylates to pyrimidine-4,6-dicarboxylates under heating with triethylamine in air is described. In this reaction, one azirine molecule undergoes formal cleavage across the C-C bond and another across the C=N bond. According to the experimental study and DFT calculations, the key steps of the reaction mechanism include nucleophilic addition of ,-diethylhydroxylamine to an azirine to form an (aminooxy)aziridine, generation of an azomethine ylide, and its 1,3-dipolar cycloaddition to the second azirine molecule.

Copper(II)-Catalyzed (3+2) Cycloaddition of 2-Azirines to Six-Membered Cyclic Enols as a Route to Pyrrolo[3,2-]quinolone, Chromeno[3,4-]pyrrole, and Naphtho[1,8-]indole Scaffolds.

A method for the [2+3] pyrroline annulation to the six-membered non-aromatic enols using 3-aryl-2-azirines as annulation agents is developed in the current study. The reaction proceeds as a formal (3+2) cycloaddition via the N1-C2 azirine bond cleavage and is catalyzed by both Cu(II) and Cu(I) compounds. The new annulation method can be applied to prepare pyrrolo[3,2-]quinoline, chromeno[3,4-]pyrrole, and naphtho[1,8-]indole derivatives in good to excellent yields from enols of the quinolin-2-one, 2-chromen-2-one, and 1-phenalen-1-one series.

Blue Light-Promoted Cross-Coupling of α-Diazo Esters with Isocyanides: Synthesis of Ester-Functionalized Ketenimines.

A metal-free scalable synthesis of functionalized ketenimines from alkyl α-(aryl/heteroaryl)-α-diazoacetates and alkyl isocyanides induced by blue light irradiation has been developed. The reaction proceeds at room temperature without any photocatalyst and provides ketenimines in moderate to good yields. Density functional theory (DFT) calculations and the experimental study showed that aryl(alkoxycarbonyl)carbenes in both singlet and triplet states can react with isocyanides but only the reaction of the former leads to the smooth formation of ketenimines.