Visible-light enabled photochemical reduction of 1,2-dicarbonyl compounds by Hünig's base

Abstract

Here, we report a visible-light enabled platform for the photochemical reduction of 1,2-dicarbonyl compounds to α-hydroxy carbonyl derivatives which utilizes diisopropylethylamine (Hünig’s base) as a reductant. This reaction tolerates a...

Photoalkylation/-arylation of ortho-Diketones with Unactivated Organic Halides

“…In the case of benzil, benzoin was isolated as the major product (not shown). 11 Based on these results, we speculate that the spatial configuration of 1,2-diones plays a vital role in the transformation. It worth noting that the rigid phenanthrene-based planar molecular frameworks of α-hydroxy ketones provide a versatile platform for further functionalization.…”

“…This reagent offers significant advantages over traditional XAT transfer reagents, such as Mn·, Sn·, and Si·, due to its low toxicity and cost-effectiveness. Our recent experiments have shown that both α-aminoalkyl and ketyl radicals can be formed in a single process via a visible light photochemical hydrogen atom transfer (HAT) process between 1,2-diketones and trialkyl amines (Scheme b) . Based on these findings, we hypothesized that the carbonyl addition reaction could be achieved via the coupling reaction of ketyl radicals and carbon radicals (formed from α-aminoalkyl radical promoted XAT process) by directly utilizing organic halides, as shown in Scheme c.…”

“…First, we tested various alkyl halides. Surprisingly, a range of primary alkyl iodides CH 3 (CH 2 ) n I (n = 1, 2, 3,9,11) were well tolerated under these conditions, giving the corresponding products in good to excellent yields (4−8, 77−94%). Moreover, alkyl iodides with alcohol, ester, or heterocycles also reacted smoothly (9, 10, and 12).…”

“…Moreover, alkyl iodides with alcohol, ester, or heterocycles also reacted smoothly (9, 10, and 12). Surprisingly, iodide, bromide, and chloride functionalized acetonitrile were all compatible in the conditions, affording the corresponding products in descending yields with the order of I, Br, Cl (11). Fluoroalkyl-containing organic compounds have attracted wide attention in the pharmaceuticals and materials science fields due to their outstanding properties, such as biological activity, metabolic stability, lipophilicity, and excellent chemical and thermal stability.…”

“…Our recent experiments have shown that both α-aminoalkyl and ketyl radicals can be formed in a single process via a visible light photochemical hydrogen atom transfer (HAT) process between 1,2-diketones and trialkyl amines (Scheme 1b). 11 Based on these findings, we hypothesized that the carbonyl addition reaction could be achieved via the coupling reaction of ketyl radicals and carbon radicals (formed from αaminoalkyl radical promoted XAT process) by directly utilizing organic halides, as shown in Scheme 1c. If such a scenario is feasible, it could establish the vital role of amines in the photochemical reaction, working as a sacrificial reagent for generating ketyl radicals and a supplier for α-aminoalkyl radicals.…”