Elaboration of phosphoramidite ligands enabling palladium-catalyzed diastereo- and enantioselective all carbon [4+3] cycloaddition

Abstract

A palladium-catalyzed diastereo- and enantioselective all carbon [4+3] cycloaddition of trimethylenemethane was developed by employing the elaborate tetrahydroquinoline-derived phosphoramidite ligand. The exclusive regioselectivity was realized by using the aromatization-driven diene indole-2,3-quinodimethanes, affording biologically important cyclohepta[b]indoles with excellent diastereo-, and enantioselectivities (up to >20:1 dr, >99% ee). Furthermore, the more challenging pyrrolidone-3,4-dienes, in the absence of aromatization force, were also compatible inthereaction, providing novel cyclohepta[c]pyrrol-1(2H)-ones with excellent regio-, diastereo-, and enantioselectivities (up to >20:1 rr, >20:1 dr, >99% ee).