Aryne‐Induced Novel Tandem 1,2‐Addition/(3+2) Cycloaddition to Generate Imidazolidines and Pyrrolidines

Abstract

A new "single-flask" method was developed for the synthesis of imidazolidines and pyrrolidines with high stereoselectivity. First, a Schiff base was arylated with an aryne. Second, an intramolecular proton transfer took place from the methylene position to the anionic aryne ring. Third, the resultant ylide reacted with a second equivalent of the same Schiff base in situ or an electron-deficient alkene through a (3+2) cycloaddition. These sequential tandem 1,2-addition/(3+2) cycloaddition reactions led to the desired heterocycles in 63-88% yields.

Current Trends towards the Synthesis of Bioactive Heterocycles and Natural Products Using 1,3-Dipolar Cycloadditions (1,3-DC) with Azomethine Ylides

“…In addition, imidazolidines 189 were analogously obtained adding 2 equiv of imino ester 107 under mild conditions (Scheme 55). 81 Both types of heterocycles were tested as antiviral agents, specifically to those emerging viral infections.…”

Domino Processes of Arynes Reacting with Three Classes of Nucleophiles for Organic Syntheses

“…For example, Yoshida and co‐workers [7] invent a method for the synthesis of benzoxazinones by treating benzyne with Schiff bases in the presence of CO 2 . Our group [8] find that arynes react with two equivalents of Schiff bases to produce imidazolidines. Furthermore, reaction of arynes with one equivalent of Schiff bases in the presence of electron‐deficient alkenes generates pyrrolidines [8] .…”

“…Our group [8] find that arynes react with two equivalents of Schiff bases to produce imidazolidines. Furthermore, reaction of arynes with one equivalent of Schiff bases in the presence of electron‐deficient alkenes generates pyrrolidines [8] . Jugé et al [9] .…”

Reactions of HDDA Benzynes with C,N‐Diarylimines (ArCH=NAr')

“…In 2006 H. Yoshida and co‐workers demonstrated the ability to access benzoxazinones 5b via trapping of the 1,3‐zwitterion by carbon dioxide using imines in which the carbon‐bound group is an alkyl moiety. In 2015 Hwu et al showed the diastereoselective formation of imidazolidines 5a and other N ‐heterocycles via trapping of the intermediate 1,3‐dipole 3e , formed via intramolecular proton transfer within 3a . Finally, in 2017 researchers in the Tian laboratory showed that 3a may be trapped by protic carbon nucleophiles in a three‐component fashion to form products of the type 5c .…”