Diastereoselective desymmetrization reactions of prochiral para-quinamines with cyclopropenes generated in situ: access to fused hydroindol-5-one scaffolds

Abstract

An interesting desymmetric [3+2] annulation reaction between p-quinamines as prochiral N-donors and 2-aroyl-1-chlorocyclopropanecarboxylates facilitated by base is reported. This successive double Michael reaction delivers a unique class of cyclopropane-fused-hydoindol-5-one frameworks...

Construction of heterocyclic rings from cyclopropenes

“…Organic & Biomolecular Chemistry works 158 under mild conditions (Scheme 27). 42 This reaction is also tolerated for the corresponding sulfonamides derived from 4-amino-4-alkylcyclohexa-2,5-dien-1-ones. This method provides an acceptable chemical yield with promising diastereoselectivities (dr up to 95 : 5).…”

“…A base-promoted diastereoselective desymmetric [3 + 2] annulation reactions of the prochiral sulfonamides with alkyl 1-chloro-2-aroylcyclopropanecarboxylates furnished a unique class of cyclopropane-fused hydroindol-5-one frameworks 158 under mild conditions (Scheme 27). 42 This reaction is also tolerated for the corresponding sulfonamides derived from 4-amino-4-alkylcyclohexa-2,5-dien-1-ones. This method provides an acceptable chemical yield with promising diastereoselectivities (dr up to 95 : 5).…”

Synthesis of Benzofuro[3,2-b]indol-3-one Derivatives via Dearomative (3 + 2) Cycloaddition of 2-Nitrobenzofurans and para-Quinamines

“…On the other hand, much attention has been paid to the application of para -quinamines as three-atom building blocks for the cascade reaction to construct nitrogen-containing heterocycles with structural diversity [ 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ]. Para -quinamines are often used as N -nucleophiles to undergo (3 + 2) cycloaddition with two-atom reaction partners, thus leading to the formation of hydroindoline-5-one scaffolds [ 49 , 50 , 51 , 52 , 53 ]. Therefore, we speculated that conducting the dearomative (3 + 2) cycloaddition reaction between para -quinamines and 2-nitrobenzofurans would lead to the fusion of hydroindoline-5-one and 2,3-dihydrobenzofuran.…”