Rhodium(III)-Catalyzed C-H Activation and Annulation with 1-Alkynylphosphine Sulfides: A Mild and Regioselective Access for the Synthesis of Bulky Phosphine Ligands

摘要

We reported herein rhodium(III)-catalyzed C-H activation and annulation reactions for the synthesis of bulky phosphine ligands by using 1-alkynylphosphine sulfides as key starting materials. In the presence of [Cp*RhCl2](2) (5 mol %) and Cs0Ac (2.0 equiv), various N-(pivaloyloxy)benzamides (3.0 equiv) could react smoothly with 1-alkynylphosphine sulfides at 40 degrees C in MeOH/CF3CH2OH cosolvent without external oxidant. Using [(CpRhCl2)-Rh-Ph](2) as catalyst, the reaction can be performed under less loading of benzamides (2.0 equiv) and milder reaction conditions (25 degrees C) with higher regioselectivity. In a sequential cydization/desulfidation process, this new method provides a variety of bulky heteroarylphosphines with an isoquinolin-1(2H)-one motif.