Palladium‐Catalyzed Cyclization Reaction of o‐Haloanilines, CO₂ and Isocyanides: Access to Quinazoline‐2,4(1H,3H)‐diones

Abstract

Quinazoline‐2,4(1H,3H)‐diones are core structural subunits frequently found in many biologically important compounds. The reaction of 2‐​aminobenzonitrile and CO2, which was frequently studied, only provided N3‐unsubstituted quinazoline‐2,4(1H,3H)‐dione compounds. Herein we report palladium‐catalyzed cyclization reactions of o‐haloanilines, CO2 and isocyanides to prepare N3‐substituted quinazoline‐2,4(1H,3H)‐diones. Electron‐rich o‐bromoanilines participated in the cyclization reaction using Cs2CO3 at high temperature, and electron‐deficient o‐bromoaniline or o‐iodoaniline substrates conducted the reaction using CsF as base to deliver corresponding quinazoline‐2,4(1H,3H)‐dione products in good yields.

Recent Advances in the Chemical Fixation of Carbon Dioxide: A Green Route to Carbonylated Heterocycle Synthesis

“…Palladium catalysis was able to perform this cascade reaction affording N3-subsituted quinazoline-2,4-(1H,3H)-diones (Scheme 30). Three papers appeared in the literature starting from o-bromoor o-iodoanilines [196][197][198]. All research groups carried out some control experiments to elucidate the reaction mechanism and all were in agreement to propose the mechanism depicted in Scheme 30.…”

“…Under these conditions, o-bromoanilines with electron-donating substituents gave satisfactory yield, but electron-withdrawing substituents afforded low yields (Scheme 30, Equation (3)). It should be noted that electron-deficient o-bromoor o-iodoanilines gave good yields with PPh 3 as the ligand, but with CsF as the base, conversely from Equation 2 (Scheme 30, Equation (4)) [198].…”

Catalytic Conversion of Carbon Dioxide through C-N Bond Formation

“…Subsequently, intermediate A undergoes an reductive elimination, deprotonation and rearrangements to generate the product. Moreover, palladium-catalyzed cyclization reactions of O -haloanilines, CO 2 and isocyanides were employed to prepare N 3-substituted quinazoline-2,4(1 H, 3 H )-dione with moderate to excellent yields (Scheme 14b) [85].…”

Silver-catalyzed carboxylative cyclization of alkynic hydrazones with carbon dioxide

“…Therefore, the development of more efficient and atom-economical approaches using CO2 as the carboxylative reagent is highly desirable. As a continuation of our interest in catalytic transformations of CO2 into fine chemicals [32][33][34], herein we report a silver-catalyzed carboxylative cyclization of alkynic hydrazones with CO2 to give 1,3,4-oxadiazin-2-ones in good yield under mild reaction conditions.…”