AlCl₃-Promoted Formal [2 + 3]-Cycloaddition of 1,1-Cyclopropane Diesters with N-Benzylic Sulfonamides To Construct Highly Stereoselective Indane Derivatives

Abstract

An unprecedented AlCl3-promoted formal [2 + 3]-cycloaddition of 1,1-cyclopropanes with readily available N-benzylic sulfonamides has been developed. Experimental evidence supports an unusual mechanism wherein the donor-acceptor cyclopropane serves as a source of 2-styrylmalonate rather than the "classical" 1,3-dipole. A broad range of 1,1-cyclopropanediesters undergo a carbocation-initiated cyclization reaction with N-benzylic sulfonamides to afford highly functionalized Indane derivatives in a fast and high-yielding procedure.

Synthesis of Indenopyridine Derivatives via MgI2‐Promoted [2+4] Cycloaddition Reaction of In‐situ Generated 2‐Styrylmalonate from Donor‐Acceptor Cyclopropanes and Chalconimines

“…On the basis of above result and literature precedent (Scheme ), we assumed that MgI 2 activates the DACs 1 and converts it into the opened ring 1,3‐zwitterion intermediate A . It further isomerises to 2‐styrylmalonate complex B .…”

“…In 2014, Wang et al . reported AlCl 3 ‐promoted formal [2+3]‐cycloaddition of DACs with N ‐benzylic sulphonamides where DACs serves as a source of 2‐styrylmalonate . Recently, Tomilov and his co‐worker reported cycloaddition of 2‐styrylmalonate, an alternative of DAC, with aldehydes, to afford dihydropyranones .…”

Scandium(III) Trifluoromethanesulfonate Catalyzed Reactions of Donor‐Acceptor Cyclopropanes with 1,1‐Diarylethylenes

“…They demonstrated cyclopropane compounds are excellent and useful building blocks in organic synthesis. Recently our group was interested in D−A cyclopropanes as useful synthons (Scheme a), as well as rare earth Lewis acid as valuable catalyst . For example, in 2017, we developed Sc(OTf) 3 catalyzed reaction of D−A cyclopropane with tertiary alcohol (Scheme b).…”

Scandium(III) Trifluoromethanesulfonate Catalyzed Selective Reactions of Donor–Acceptor Cyclopropanes with 1,1‐Diphenylethanols: An Approach to Polysubstituted Olefins

“…Moreover, D–A cyclopropanes can also act as sources of 1,2‐ and 1,4‐dipoles under Lewis acid conditions. Recently, our group revealed that D–A cyclopropanes could undergo reactions as less‐developed 1,2‐dipoles in formal [2+3]‐cycloaddition reactions.…”