Palladium-Catalyzed Sequential Heck Reactions of Olefin-Tethered Aryl Iodides with Alkenes

Abstract

An efficient approach to functionalized (E)-3-cinnamyl-3-methyl-2,3-dihydrobenzofurans and (E)-(3-methyl-2,3-dihydrobenzofuran-3-yl)­but-2-enones has been developed through a Pd-catalyzed one-pot cascade process involving two sequential Heck reactions, that is, an intramolecular Heck reaction of olefin-tethered aryl iodides and an intermolecular Heck reaction with substituted styrenes and α,β-unsaturated ketones. As a result, a series of desired products were obtained in moderate to good yields and with exclusive E-form selectivities.

Pd/Cu-catalyzed cascade Heck-type reactions of alkenyl halides with terminal alkynes toward substituted pyrrolidine analogues

“…Based on this reaction pattern, fruitful transformations have been extensively investigated. 6 However, the majority of these methods have focused on the reactions of aryl halide-tethered alkenes. In contrast, the reactions of halogen or halogen-like substituted diolefins are quite limited mainly due to the challenge in the oxidative addition of alkenyl halides to low-valent transition metals.…”

“…Based on previous literature on Heck-type reactions 5,6 and reports involving alkynyl copper species, 11 a plausible reaction pathway is proposed, as shown in Scheme 5. Initially, oxidative addition of alkenyl bromide 1a to Pd(0) gives the Pd( ii ) species 1a-I , which coordinates with intramolecular alkene.…”

Development of novel transition metal-catalyzed synthetic approaches for the synthesis of a dihydrobenzofuran nucleus: a review

“…In 2022, Guo 77 et al successfully designed a new Pd-catalyzed method for the synthesis of substituted 3,3-disubstituted-2,3-dihydrobenzofurans via the reaction of olefin-tethered aryl iodides 102 with α,β-unsaturated ketones 114 and substituted styrenes 115 . In their one-pot synthetic methodology, two sequential Heck couplings took place, leading to the construction of dihydrobenzofuran skeletons 116 and 117 .…”