Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds

Abstract

The sensitized photoexcitation of 2-diazocyclopentane-1,3-diones in the presence of THF leads to the insertion of the terminal N-atom of the diazo group into the α-С–Н bond of THF, producing the associated N-alkylhydrazones in yields of up to 63–71%. Further irradiation of hydrazones derived from furan-fused tricyclic diazocyclopentanediones culminates in the cycloelimination of furans to yield 2-N-(alkyl)hydrazone of cyclopentene-1,2,3-trione. By contrast, the direct photolysis of carbocyclic diazodiketones gives only Wolff rearrangement products with up to 90–97% yield.

Definition of the Pnictogen Bond: A Perspective

“…Additionally, the attractive intramolecular interaction between arsenic and chlorine in crystalline 3,4,5,6-tetrachloro-1,2-diarsa-closo-hexaborane is a pnictogen bond, not a halogen bond [91]. The pnictogen-centered Pn•••A intermolecular interactions between interacting units in selected crystalline solids shown in Figure 1d-i [100]; (b) 3',3'',3'''-Phosphinetriyltripropionitrile [101]; (c) trifluoroamine [102]; (d) antimony triiodide molecular sulfur S8 [103]; (e) bis(tetrakis(4-methylphenyl)-antimony) hexabromo-iridium [104]; (f) tris(4-methylphenyl)-(2-(phenylsulfanyl)phenyl)-antimony tetrafluoroborate [42]; (g) diphenylphosphenium bromide [105]; (h) 4-(di-iodoarsino)anilinium 4methylbenzenesulfonate [106] [107] (j) 5-oxo-4,5-dihydrotetrazol-1-ide azane oxide [40]; (k) (2,2'-[sulfanediylbis(methylene)]di(phenyl))-iodo-bismuth(III) [108]; (l) 10-(4-fluorophenyl)-10H-phenoxarsinine [109]; (m) 2-diazonio-1-oxo-3a,4,5,6,7,7a-hexahydro-1H-4,7-methanoinden-3-olate [110]; (n); molecular nitrogen [111]; (o) naphthalene-2-diazonium-3-carboxylate [112]; and (p) azido-nitramino-carbonyl [50]. Selected bond lengths and bond angles are in Å and degrees, respectively.…”

Visible-Light-Mediated (sp3)Cα–H Functionalization of Ethers Enabled by Electron Donor–Acceptor Complex

“…Based on the previous literature, , we hypothesized that an α-diazo-β-keto compound might act as a good N-terminal acceptor. Therefore, we geared our investigation by choosing α-diazo-β-keto ester 1a as a model substrate in THF (0.5 M) 2a at room temperature to commence the visible-light promoted C–H amination protocol.…”

“…This resulted in synthesizing a wide range of hemiaminal ethers where α-diazoketones and dialkyl azodicarboxylates served as an amination reagent (Scheme 1b) guided by catalytic EDA system. 45,46 ■ RESULTS AND DISCUSSION Based on the previous literature, 32,33 we hypothesized that an α-diazo-β-keto compound might act as a good N-terminal acceptor. Therefore, we geared our investigation by choosing α-diazo-β-keto ester 1a as a model substrate in THF (0.5 M) 2a at room temperature to commence the visible-light promoted C−H amination protocol.…”

“…In contrast, Nikolaev et al demonstrate photosensitizer guided and UV-light mediated insertion of α-C–H bond of tetrahydrofuran (THF) into the terminal N-atom of the diazo group, suffering from a mixture of products with limited substrate scope ( Scheme 1 a). 32 , 33 In recent years, seminal work was done by the Yu and Xu groups individually with photoredox catalysis. Concurrently, two reports from the Lu group demonstrate the exploitation of aryl diazoacetates to synthesize hydrazone moieties under cobalt catalysis.…”

A Metal-Free Cycloaddition of α-Diazoacetates with Amino Acid-Derived NHPI Esters for the Facile Synthesis of 1,2,4-Triazoles

“…5 Nikolaev and co-workers developed a photochemical coupling of 2-diazocyclopentane-1,3-diones with tetrahydrofuran (THF). 6 Recently, we developed the metal-free photoredox decarboxylative C(sp 3 )−N coupling of α-diazoacetates with alkyl N-hydroxyphthalimide (NHPI) esters to access structurally and functionally diverse N-alkyl hydrazones. 7 1,2,4-Triazoles belong to a privileged class of five-membered aromatic heterocycles containing three nitrogen atoms that exhibit a broad spectrum of biological activities.…”