Exploring the Reactivity of Propargylic Ester: Acyloxy and Acyl Migratory Rearrangement Relay Enabled by Formal Double Isocyanide Insertion

Abstract

A rearrangement of propargylic pivalate with isocyanide under transition metal-free conditions is disclosed. Intermolecular 1,3-acyloxy and acyl migration enables the rapid formation of a C(sp 2 )À C(sp 3 ) bond from a CÀ O bond and the synthesis of polysubstituted 5-iminopyrrolones.

Reactions Involving Multiple Isocyanide Insertions

“…synthesized polysubstituted 5‐iminopyrrolones 241 in low to excellent yields (38–96%) via rearrangement of propargylic pivalates 236 with isocyanides 2 under metal‐free conditions in toluene at 140 °C (Scheme 32). [48] According to control experiments, initially, propargylic pivalates 236 undergo the nucleophilic addition by isocyanides 2 followed by the elimination of pivalate anion to produce the active allene intermediates 237 . Then, Michael addition of isocyanides 2 to these intermediates 237 gave ketenimine intermediates 238 which undergo the addition of pivalate anion to generate intermediates 239 .…”

Construction of Tetrazole Derivatives via Sequential Ugi‐N3/Pd‐Catalyzed Isocyanide Insertion Reactions

“…For example, Jiang's group has notified a novel palladium‐catalyzed tandem cyclization to benzofuran derivatives via 1‐(allyloxy)‐2‐ethynylbenzene products with isocyanides in the presence of water in 2018 [14c] . Subsequently, a rearrangement reaction of propargylic pivalate with double isocyanides under transition metal‐free conditions was developed by Li's group in 2021 [14e] . Recently, Ren's group disclosed an efficient way to synthesize indole derivatives by Pd‐catalyzed double isocyanide insertion reactions in moderate to good yields [14f] .…”

A Facile Synthesis of Indole Derivatives by a Palladium‐Catalyzed Process Initiated from Ugi Adducts and their Antifungal Activities

“…Subsequently, Qiu and co‐workers described an unprecedented route for the synthesis of 2‐amino‐4‐cyanopyrrole derivatives via palladium‐catalyzed double isocyanide insertion of alkynyl imines in 2019 [14] . Recently, Li disclosed a rearrangement of propargylic pivalate with isocyanide under transition metal‐free conditions to construct polysubstituted 5‐iminopyrrolones [15] . Inspired by the beautiful works above, our research group attempted to develop double isocyanide insertion reaction to synthesize heterocyclic compounds.…”