Photocatalytic 1,4-Addition of Aromatic Aldehydes or Ketones via Umpoled Carbinol Anions

Abstract

A 1,4-addition reaction of aromatic aldehydes and ketones to electron-deficient olefins was achieved under photocatalytic conditions. In the reaction, an umpoled carbinol anion generated in situ through two successive one-electron reductions of the carbonyl compound reacted nucleophilically with the electron-deficient olefin. Various electron-deficient aromatic aldehydes and ketones successfully underwent the reaction to afford the corresponding -functionalized alcohols.

Multielectron Reduction of Esters by a Diazabenzacenaphthenium Photoredox Catalyst

“…Compared with photoinduced radical reactions, the development of photocatalytic molecular transformations via ionic (anion/cation) species generated through a multielectron-transfer process has received scant attention . We recently achieved the generation of α-hydroxy carbanion (carbinol anion) species from aldehydes and ketones through a successive double SET, thereby realizing an umpoled electrophilic substitution of the carbonyl group. , However, the photocatalytic reduction of esters to form carbinol anions is a formidable challenge because it requires an unprecedented successive quadruple SET process; as a result, this reaction remains undeveloped . Here, we report the first photocatalytic four-electron reduction of esters by using a novel diazabenzacenaphthenium photocatalyst in which the resulting carbinol anions react with water and a second carbonyl compound, thereby providing a protonative reduction (Scheme A) and a cross-pinacol coupling (Scheme B).…”

Manganese/Enzyme Sequential Catalytic Pathway for the Production of Optically Active γ-Functionalized Alcohols

“…Given their wide applications, efficient synthesis of γ-functionalized alcohols is of utmost importance. For decades, the construction of γ-functionalized alcohols has primarily relied on hydrogenation of β-functionalized ketones, conjugate addition followed by reduction, alkene activation involving (homo)­allylic alcohols, and 1,3-difunctionalization of alkenes . Among them, the synthesis of γ-functionalized alcohols via the formation of C–C bonds is an appealing method.…”