Asymmetric syntheses of spiro[benzofuro-cyclopenta[1,2-b]indole-indoline] scaffolds via consecutive cyclization

An efficient method to construct enantioenriched spiro[benzofuro-cyclopenta[1,2-b]indole-indoline] scaffolds via consecutive cyclization is described here. The new scaffolds possess five successive chiral stereogenic centers and two spiroheterocycles. A range of highly enantioenriched scaffolds has been obtained with up to 93% yield, 99% ee and >19 : 1 d.r. catalyzed by Bronsted acid catalysts.

Automated summary

An efficient method for constructing enantioenriched spiro[benzofuro-cyclopenta[1,2-b]indole-indoline] scaffolds via consecutive cyclization is described. The resulting scaffolds possess five successive chiral stereogenic centers and two spiroheterocycles, with high yields and enantiomeric excess.