Asymmetric organocatalytic (3 + 2) annulation of propargylic alcohols with indolylnaphthalenols: synergistic construction of axial and central chirality†

Abstract

Organocatalytic enantioselective construction of chiral spiro N,N-acetal carbon stereocenters and axially chiral 3-arylindoles has been achieved via a chiral phosphoric acid (CPA)-catalyzed (3 + 2) annulation of α-(3-isoindolinonyl) propargylic alcohols with 1-(3-indolyl)naphthalen-2-ols, affording a broad scope of pyrrolo[1,2-a]indoles bearing both enantioenriched spiro isoindolinone-indoline and atropisomeric naphthalenol frameworks. Based on control experiments and our previous work, a possible mechanism was proposed accordingly.