Frustrated Lewis Pair-Mediated Cycloisomerization of Propargylaniline and Aryl Propargyl Ether Derivatives via a 6-endo-dig Cyclization/Dehydrogenation Sequence

Abstract

An efficient FLP-mediated cycloisomerization is described, providing easy access to quinolinium and chromenylium derivatives by treatment of readily available propargylanilines and aryl propargyl ethers with Lewis acidic boranes, respectively. The reaction proceeds via a 6-endo-dig cyclization/dehydrogenation sequence. The heteroatom functions serve as Lewis bases in combination with Lewis acidic boranes to effect synergistic activation of an alkynyl triple bond and a C−H bond.