Photochemistry of Benzotriazoles: Generation of 1,3-Diradicals and Intermolecular Cycloaddition as a New Route toward Indoles and Dihydropyrrolo[3,4-b]Indoles

Abstract

Irradiation of benzotriazoles 1a-e at λ = 254 nm in acetonitrile solution generated the corresponding 1,3-diradicals which underwent intermolecular cycloaddition with maleimides to afford the corresponding dihydropyrrolo [3,4-b]indoles and with acetylene derivatives to afford indoles as the major products. This offers an interesting and simple access to such ring systems of potential synthetic and biological interest. The structures of the photoproducts were established spectroscopically and by single crystal X-ray crystallography.

Convenient One‐Step Synthesis of Benzotriazolylsuccinimides in Melt

“…The similar peaks of the minor (benzotriazol‐2‐yl)‐succinimide residues appear also in the 13 C NMR spectra of 2a and 2c . For 1a , this compound was investigated by authors who observed the 13 C NMR peaks of 1a that are similar to the 13 C NMR ones of the minor (benzotriazol‐2‐yl)‐succinimide residues of 2b , 2c . The ratios of an integral intensity of the C(3′)H and C(3‴)H protons in the 1 H NMR spectrums of 2a , 2b , 2c were ascertained to be 7.0 (for 2a ), 4.5 (for 2b ), and 7.0 (for 2c ), proving additionally the lesser content of the (benzotriazol‐2‐yl)‐succinimide residues.…”

“…Thus, the NMR investigations of 1 and 2a , 2b , 2c , along with a comparison with the NMR data of 1a , have revealed that 1H‐benzotriazoles interact with maleimides in melt at high temperatures to afford benzotriazolylsuccinimides comprising both major (benzotriazol‐1‐yl)‐succinimide residue and minor (benzotriazol‐2‐yl)‐succinimide residue.…”

“…The absence of toxic, flammable, and corrosive solvents, catalysts as well as a lack of by‐products evolution are the advantages of such reaction in terms of the green chemistry and the atom efficiency. To the best of our knowledge, information about such melt reaction between 1H‐benzotriazoles and maleimides in the scientific literature is absent, excepting the works of the authors of the presented article and other authors who referenced to our previous work . This article is devoted to the continuation of our work concerning the melt synthesis and the investigation of benzotriazolylsuccinimides.…”

The Solid-State Structures of Cyclic NH Carboximides

“…It is interesting to note the variation among these examples in whether it is the carbonyl nearer or more remote from the substituent that is involved in bonding. In compounds 39 [45] and 40 [46] (Figure 14) the NH of the imide is linearly bonded to a remote heterocyclic nitrogen in the next molecule (pattern E, C (10) and C (7), respectively). One reported structure, the compound 41 [47], forms linear C (7) chains with the NH of the imide interacting with a remote ketone oxygen on the next molecule (pattern F).…”

A Benzoquinone Imine Assisted Ring‐Opening/Ring‐Closing Strategy of the RCOCHN1N2 System: Dinitrogen Extrusion Reaction to Benzimidazoles

“…Benzotriazoles (BTZs), owing to their diverse roles in chemical transformations and in the discovery of bioactive scaffolds, have proven to be intriguing substrates . However, owing to their innate tendency to exist as diazonium salts and to their high structural stability, the ring‐opening chemistry of benzotriazoles has not been well studied . Recently, our group established a novel route for the synthesis of 6‐aminophenanthridines through a 2‐oxo driven N 2 elimination induced decarbonylative cyclization strategy.…”