Atroposelective Synthesis of 2, 2′‐Bis(arylamino)‐1, 1′‐biaryls by Oxidative Iron(III)‐ and Phosphoric Acid‐Catalyzed C−C Coupling of Diarylamines. Issue 6 (27th November 2022) - Fritsche, Raphael F.
Abstract: We describe an iron‐catalyzed asymmetric oxidative C−C coupling of diarylamines which proceeds at room temperature with air as final oxidant. Using hexadecafluorophthalocyanine‐iron(II) as catalyst in the presence of catalytic amounts of an axially chiral biaryl phosphoric acid, the resulting chiral 2, 2′‐diamino‐1, 1′‐biaryls are obtained in up to 90 % ee as confirmed by chiral HPLC. A detailed mechanism has been proposed with a radical cation‐chiral phosphate ion pair as key intermediate leading to the observed asymmetric induction. Abstract : The asymmetric oxidative C−C homocoupling reaction of diarylamines using air as final oxidant is catalyzed by a hexadecafluorinated iron‐phthalocyanine complex and an axially chiral biaryl phosphoric acid. A radical cation‐chiral phosphate anion pair is proposed as key intermediate responsible for the asymmetric induction.