Polynuclear gold(i) complexes in photoredox catalysis: understanding their reactivity through characterization and kinetic analysis

Abstract

The light mediated reduction of unactivated carbon–halogen bonds using polynuclear gold(i) complexes provides a mild and temporally controlled route to the generation of C–H, and C–C bonds.

Visible‐Light‐Initiated Manganese Catalysis for C−H Alkylation of Heteroarenes: Applications and Mechanistic Studies

“…Comprehensive optimization revealed that quantitative conversion of 1 to 2a can be achieved with only 2equivalents of the alkyl iodide,1 5mol %M n 2 (CO) 10 ,a nd 0.1 equivalents of TFA (Table 1, entry 6, see the Supporting Information for the full optimization table). [1][2][3][4][5][6][7][8] Also noteworthy is the fact that the use of an unactivated alkyl bromide did not result in CÀHa lkylation of lepidine 1 (See Figure 2c). [1][2][3][4][5][6][7][8] Also noteworthy is the fact that the use of an unactivated alkyl bromide did not result in CÀHa lkylation of lepidine 1 (See Figure 2c).…”

“…Gratifyingly,i tw as found that this mild protocol tolerates simple to relatively complex functionalized primary (2b-2g), secondary (2h-2q), and tertiary (2r-2s)u nactivated iodoalkanes in moderate to excellent yields (19-98 %). [2,[4][5][6][7] Furthermore,t his technology was fully applied to other heterocyclic cores (pyridine,phthalazine,and benzimidazole) (Table 2b, 3-6,4 3-60 %y ield). [3] Them ildly acidic conditions allowed the introduction of acid-sensitive groups,s uch as oxetane,asugar moiety,a zetidine,a nd tert-butyl carbamate (Boc group), which provide synthetic handles for further derivatization and structure-activity relationship (SAR) studies ( Table 2, 2g, 2j, 2k, 2l, 2o, 2q, 3, 4,and 5).…”

“…[1,2] Owing to increasing interest in alkyl-functionalized heterocycles in drug discovery,C À H alkylation of heteroarenes has impacted medicinal chemistry strategies. [2,[4][5][6][7] Non-photomediated Minisci approaches often involve the use of an excess oxidant, peroxide,e xcess acid, and high temperature. [2,[4][5][6][7] Non-photomediated Minisci approaches often involve the use of an excess oxidant, peroxide,e xcess acid, and high temperature.…”

“…[6] Theu se of aprecious metal catalyst, external oxidant, and the inability to use the method developed by Chen and colleagues to add tertiary alkyl radicals to heteroarenes calls for further development of this process. [7] However,t he elegant photoredox method developed by McCallum and Barriault requires the use of ar are and expensive photoredox catalyst [Au 2 (dppm) 2 ]Cl 2 and irradiation with high-energy UV light. [7] However,t he elegant photoredox method developed by McCallum and Barriault requires the use of ar are and expensive photoredox catalyst [Au 2 (dppm) 2 ]Cl 2 and irradiation with high-energy UV light.…”

Neue Entwicklungen auf dem Gebiet der Minisci‐Reaktion

“…[132] Da auch photoangeregtes [Au 2 (dppm) 2 ]Cl 2 Alkylbromide durch einen photoinduzierten Innensphären-SET reduzieren kann (Schema 55, mechanistische Überlegungen), [133] nahmen die Autoren an, dass sich dieser Ansatz auch in einen insgesamt redoxneutralen Minisci-Mechanismus integrieren lässt. [132] Da auch photoangeregtes [Au 2 (dppm) 2 ]Cl 2 Alkylbromide durch einen photoinduzierten Innensphären-SET reduzieren kann (Schema 55, mechanistische Überlegungen), [133] nahmen die Autoren an, dass sich dieser Ansatz auch in einen insgesamt redoxneutralen Minisci-Mechanismus integrieren lässt.…”