Copper-catalyzed carbene insertion and ester migration for the synthesis of polysubstituted pyrroles

Abstract

Copper–catalyzed carbene insertion/ester migration/cyclization of enaminones and α-diazo compounds occurred efficiently, affording 2-ester polysubstituted pyrroles under mild conditions in moderate to good yields. Substituents functionality are well tolerated and 13C-labelled...

Copper‐Catalyzed Olefinic C(sp2)−H Activation/Carbene Insertion/Ester Hydrolysis/Cyclization with Aryl Diazo Esters for the Synthesis of Multisubstituted Furanones

“…However, carbenes insertion into olefinic C−H bonds are very limited, [18] presumably due to the competing cyclopropanation of the alkene and allylic C−H activation under diverse reaction conditions. In our previous work, we found carbene insertion into C=C bond of enaminone could occur smoothly to form 2‐ester polysubstituted pyrrole and iminofuran (Scheme 1b) [16a–b] . Unexpectedly, in this work, the insertion of carbenes into olefinic C−H bond not C=C bond was found when morpholinoyl‐derived enaminone 1 a reacted with diazo compound 2 a , which might be steric effect of bulky morpholinoyl group.…”

Pd-Catalyzed Triple-Fold C(sp2)–H Activation with Enaminones and Alkenes for Pyrrole Synthesis via Hydrogen Evolution

“…With the catalysis of proper transition metal reagents, stable enamines such as enaminones, enaminoesters, enaminonitriles, etc. have been used to couple alkynes, alkenes, diazoesters/hydrazones, or functionalization of intramolecular C–H bonds for the synthesis of diversely functionalized pyrroles. Interestingly, although a plethora of different alkenes have been successfully used as reaction partners of stable enamines for pyrrole synthesis, no known method has hitherto been found to tolerate the transformation of acrylates for the synthesis of corresponding pyrrole products.…”

Synthesis of methyl 1,5‐diaryl‐1H‐pyrrole‐2‐carboxylates via acid‐catalyzed ring‐opening/ring‐closure sequence

“…One‐pot preparation of pyrroles was achieved via copper (II)‐catalyzed [4+1] annulation of propargylic amines with N , O ‐acetals, or with alkyl/aryl glyoxylates [13,14]. In recent years, transition metal‐catalyzed reactions of 2‐diazoesters are successfully established to prepare pyrroles, such as the dual copper and dirhodium‐catalyzed reaction of tert‐ butyldimethylsilyl‐substituted vinyldiazoacetate with nitrones, copper‐catalyzed condensation of imines with α‐diazo‐β‐dicarbonyl compounds, copper(II)‐catalyzed reaction of enaminones with 2‐diazo‐2‐arylacetate, AgOTf‐catalyzed reaction of enaminones with aryl diazoesters, and rhodium(II)‐catalyzed intramolecular N─H insertion reactions of δ‐amino‐γ,γ‐difluoro‐α‐diazo‐β‐ketoesters [15–19]. In addition, one‐pot acid‐catalyzed reaction between 2,3‐diketoester, imine, and aldehyde produces fully substituted 3‐aminopyrroles [20].…”