K₂S₂O₈-glucose mediated oxidative coupling of alcohols with indoles for synthesis of bis(indolyl)methanes in water

Abstract

The use of inexpensive K2S2O8 in water at room temperature for synthesis of bis(indolyl)methanes (BIMs) from simple indoles and alcohols is reported. The key step involves the conversion of alcohols...

K2S2O8‐Mediated C‐3 Formylation of Imidazopyridines Using Glyoxylic Acid

“…Following the inferences of control experiments (scheme 3) and prior literature reports, [5,[21][22][23][24] we tried to establish a plausible reaction mechanism of our developed methodology (Scheme 4). The reaction proceeds with the condensation of glyoxylic acid (2) to 1 a followed by its decarboxylation.…”

“…[21] Although several reports are on the formylation of indoles and small heterocyclics, there is no such report on the use of glyoxylic acid for formylation of imidazopyridines. In continuation of our interest in the functionalization of imidazo[1,2-a]pyridines [5] and persulfate-based method developments, [22,23] herein, we report a highly efficient C-3 formylation of imidazo[1,2-a]pyridines by using glyoxylic acid and persulfate.…”

K2S2O8‐Glucose‐Mediated Metal‐Free Oxidative Trifluoromethylation of Indoles with Langlois’ Reagent on the C2 Position

“…[25][26][27][28][29][30][31][32] Addition of glucose leads to activation of K 2 S 2 O 8 at room temperature due to donation of an electron to the persulfate by the former, which itself gets oxidised. [33][34] By far, we have observed only one report on K 2 S 2 O 8 -promoted activation of CF 3 SO 2 Na for radical oxytrifluoromethylation of alkenes in aerobic conditions. [35] But none such reports are available on indole derivatives.…”

“…Persulfate (S 2 O 8 2− ) is a commercially available oxidizing agent, extensively involved in a wide range of oxidative organic transformations [25–32] . Addition of glucose leads to activation of K 2 S 2 O 8 at room temperature due to donation of an electron to the persulfate by the former, which itself gets oxidised [33–34] . By far, we have observed only one report on K 2 S 2 O 8 ‐promoted activation of CF 3 SO 2 Na for radical oxytrifluoromethylation of alkenes in aerobic conditions [35] .…”

Potassium Persulfate‐Glucose Mediated Synthesis of (3)‐S‐Arylthioindoles from Indole and Thiophenols in Water

“…The proposed mechanism of the reaction is shown in Scheme 4. Initially, glucose facilitates the generation of thiol and indole radicals A and B , respectively, in the presence of potassium persulfate in water [7i,k,l] . Subsequently, these radicals undergo a coupling reaction and generate the intermediate C , which is converted into the desired product D via 1,3‐hydrogen shift.…”