Orthogonal Regulation of Nucleophilic and Electrophilic Sites in Pd‐Catalyzed Regiodivergent Couplings between Indazoles and Isoprene

Abstract

Depending on the reactant property and reaction mechanism, one major regioisomer can be favored in areaction that involves multiple active sites.H erein, an orthogonal regulation of nucleophilic and electrophilic sites in the regiodivergent hydroamination of isoprene with indazoles is demonstrated. Under Pd-hydride catalysis,t he 1,2-or 4,3insertion pathway with respect to the electrophilic sites on isoprene could be controlled by the choice of ligands.Interms of the nucleophilic sites on indazoles,t he reaction occurs at either the N 1-o rN 2-position of indazoles is governed by the acid co-catalysts.P reliminary experimental studies have been performed to rationalizet he mechanism and regioselectivity. This study not only contributes ap ractical tool for selective functionalization of isoprene,b ut also provides ag uide to manipulate the regioselectivity for the N-functionalization of indazoles.

Bu4NHSO4‐Catalyzed Direct N‐Allylation of Pyrazole and its Derivatives with Allylic Alcohols in Water: A Metal‐Free, Recyclable and Sustainable System

“…In Path A, ionization of conjugate pyrazole in the presence of catalyst affords pyrazole anion through hydrogen bonding, which will attack the carbocation to release the product. On the other hand, pyrazole is considered as a soft nucleophile because the pKa of NH in pyrazole is about 19.8 [12e,f,29] . Therefore, VI or VII formed the hydrogen bonding effect with water and catalyst will act as the soft nucleophile and add directly to the allylic moiety to produce transition state IV shown in Path B.…”

Nickel-catalyzed divergent Mizoroki–Heck reaction of 1,3-dienes

“…As extensive feedstocks in nature and industry, the catalytic functionalization of 1,3-dienes is a straightforward strategy to build up the molecular complexity [24][25][26][27][28][29][30][31][32][33][34][35][36][37] . However, compared with that of mono alkenes, the arylation of dienes brings extra challenges in selective control owing to the existence of an additional C = C bond [38][39][40] .…”