Photochemical transformations of diazocarbonyl compounds: expected and novel reactions

Blue light-promoted photolysis of aryldiazoacetates

“…Although this photolysis phenomenon is well known for other diazocompounds using UV-light, 9 , 16 , 18 one can note here that the presence of a donor group at the aryldiazoacetates 1a and 1b (or the removal of an acceptor group, as one can observe the same trend comparing the UV-Vis absorption spectra of 2a and 2b ) is responsible for a significant bathochromic shift in their UV-Vis absorbance spectra, thus allowing the photolysis process to occur in the visible region. 10 , 16 …”

“…In contrast to the numerous protocols reported on thermal processes, photochemical studies with diazocompounds have been performed mostly several decades ago, 9 and modern applications are relatively scarce. 10 , 11 Among these, Suero and co-workers have recently demonstrated that a hypervalent iodine reagent carrying a diazoacetate moiety could be employed in a photoredox-catalyzed protocol for the C–H functionalization of a variety of arenes.…”

Blue LED Induced Manganese (I) Catalysed Direct C2−H Activation of Pyrroles with Aryl Diazoesters

“…Transfer of carbenes from diazo moieties into many heterocycles is a useful transformation in organic synthesis. [1,2] This transformation involves insertion into CÀ X bonds (X: halides or H), addition to CÀ Y bonds (Y: C, N) or cyclopropanation of À C=CÀ bond. They have been utilized to modify various heterocyclic substrates such as pyrroles, indoles, furans and thiophenes.…”

[3+2]‐Cycloaddition of Catalytically Generated Pyridinium Ylide: A General Access to Indolizine Derivatives

“…With the rapid developments in synthetic photochemistry, the photochemical reaction of diazo compounds via free carbene intermediates has been re-emerged in the past years. [14,15] The early example of the formation of pyridinium ylide from diazo compounds and pyridines under photocatalysis or thermocatalysis was disclosed by Platz [16] and Surpateanu, [17] respectively. However, the only reaction with isolated cycloadduct was reported by Platz: photolysis of diazirine 1 with pyridine 2 a to produce 3 in about 30% yield via sequential formation of free carbene, pyridinium ylide, and [3 + 2]-cycloaddition with dimethylacetylenedicarboxylate (DMAD) followed by aromatization via elimination of a molecule of HCl (Scheme 4.…”