Oxidative Alkenylation of Fused Bicyclic Heterocycles

Abstract

The aim of this review is to highlight the advances made in the C–H/C–H functionalization of 5,5‐fused‐heterocyclic systems and 5,6‐fused‐heterocyclic systems such as indoles (C2, C3, C4, and C7 alkenylation), carbazoles, azaindoles, benzofurans, benzothiophenes, enzothiazoles, benzoxazoles, benzimidazoles, imidazopyridines, indolizines, indazoles (C3 and C7 alkenylation), and caffeine. The reports on oxidative alkenylation of 6,6‐fused‐heterocyclic systems including quinoxaline N‐oxides, quinoxalines, quinolones, isoquinolones, quinolines, 1,4‐benzoquinones, benzo[b][1,4]oxazines, benzo[b][1,4]thiazines, chromones, flavones, coumarins, 4H‐pyrido[1,2‐a]pyrimidin‐4‐ones, 1‐(2H)‐phthalazinones, phosphachromones, phosphacoumarins and sulfocoumarins will be also discussed.

Iron-Catalyzed Ortho C–H Homoallylation of Aromatic Ketones with Methylenecyclopropanes

“…Alkenes are one of the most versatile functional groups in organic synthesis, and numerous methods have been developed for direct introduction of alkenyl and allyl groups. In contrast, the corresponding C–H homoallylation has been challenging due to facile isomerization of the homoallylation products and β-hydride elimination of homoallylmetal intermediates into metal hydrides and 1,3-dienes.…”

Pd-Catalyzed Intermolecular Dehydrogenative Heck Reactions of Five-Membered Heteroarenes

“…The topic continued to retain the attention of researchers resulting into papers with different N-protecting groups and experimental conditions. Reviews not limited to palladium catalysis and DHR have been published [77][78][79]. As pointed in the introduction chapter, we will limit the examples to the DHRs of the heterocycle (For reactions at C4, C5, C6, and C7 positions of the benzenoid ring, see [18]).…”

Recent advances in catalytic silylation of hydroxyl‐bearing compounds: A green technique for protection of alcohols using Si–O bond formations

“…[38][39][40][41] Heteroaromatic N-oxides which provide satisfactory electronic environments in the transition state-founded in the reaction-have the capability to work as powerful electron-pair donors. [92][93][94][95] There are two features: the oxygen atom nucleophilicity in N-oxides and a high affinity of silicon to oxygen which aim at representing perfect properties in order to develop a synthetic methodology based on nucleophilic activation of organosilicon reagents. [96][97][98][99] Due to the N-O bond polarization, one can classify the heteroaromatic N-oxides properties as strong Lewis bases.…”