Hydroxylamine‐<i>O</i>‐Sulfonic Acid (HOSA) as a Redox‐Neutral Directing Group: Rhodium Catalyzed, Additive Free, One‐Pot Synthesis of Isoquinolines from Arylketones

Abstract

A new application of hydroxylamine‐ O ‐sulfonic acid (HOSA) has been discovered whereby aromatic ketones react with HOSA and alkynes to form isoquinolines in the presence of a Rh III catalyst. This C–H/N–O annulation methodology gives excellent yields even without any silver additive, acid/base or metal oxidant. This is the first report wherein a directing group is simultaneously forming in situ, acting as acid additive, and also as an internal oxidant.