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

Abstract

Herein, we have reported a blue LED mediated manganese pentacarbonyl bromide catalysed incorporation of carbene moieties from aryl diazoesters onto 1H-pyrroles via their selective C2À H activation. A manganese metal-carbene has been identified as the active catalyst to facilitate the reaction. Eighteen mono substituted pyrrole derivatives were isolated in good to excellent yields (67!82%) and the disubstituted products were also formed in minor quantities (5 to 8%). HPLC based kinetics study enabled optimization of the reaction. Control experiments, FT-IR, NMR and GC-MS based characterization elucidated the putative reaction mechanism.

Blue-Light-Induced Iron-Catalyzed α-Alkylation of Ketones

“…Among the photoinduced approaches, one elegant application is to use a single catalyst to harvest the visible light and break/form bonds by exploiting the inner coordination sphere of a transition metal complex. Although, until now, the C–H functionalization is at the forefront of this emerging chemistry, the application of chromophoric transition metals in hydrogen autotransfer methodology could circumvent some of its limitations (such as the harsh reaction conditions) and open new avenues in catalysis.…”

Photoredox catalysis leading to triazolo-quinoxalinones at room temperature: selectivity of the rate determining step

“…As discussed in the literature, [55][56][57][58] by irradiation with blue light, [59][60][61][62] the Ru(bpy) 3 Cl 2 catalyst can be excited to the S 1 state, being 2.66 eV higher in energy than the S 0 state. After relaxation, it can achieve the T 1 state, with a relative energy of 1.96 eV with respect to the S 0 state as shown in Fig.…”

Recent advances in transition-metal-catalyzed carbene insertion to C–H bonds

“…Blue LED-induced, manganese( i )-catalyzed C(2)–H functionalization of pyrroles was achieved through carbene insertion. 345 With 1 mol% Mn(CO) 5 Br as the catalyst, and NaOAc (2 equiv.) as the additive in CH 2 Cl 2 , the reaction of N -unprotected pyrroles and donor/acceptor or acceptor/acceptor diazo compounds proceeded smoothly under blue LED irradiation, affording the C(2)–H functionalization products 338 in 67–82% yields with minor formation of the corresponding dialkylation products (5–8%) when the C5 position was not substituted (Scheme 100).…”