Atroposelective Synthesis of 2,2′‐Bis(arylamino)‐1,1′‐biaryls by Oxidative Iron(III)‐ and Phosphoric Acid‐Catalyzed C−C Coupling of Diarylamines**

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.