Cationic Ir/Me‐BIPAM‐Catalyzed Asymmetric Intramolecular Direct Hydroarylation of α‐Ketoamides

Abstract

Asymmetric intramolecular direct hydroarylation of α-ketoamides gives various types of optically active 3-substituted 3-hydroxy-2-oxindoles in high yields with complete regioselectivity and high enantioselectivities (84-98% ee). This is realized by the use of the cationic iridium complex [Ir(cod)₂](BAr(F)₄) and the chiral O-linked bidentate phosphoramidite (R,R)-Me-BIPAM.

Transition‐Metal‐Catalyzed C−H Functionalization for Construction of Quaternary Carbon Centers

“…Shibata and co-workers [71] in 2009 report as ingle case of intramolecular hydroarylation of N-aryl pyruvamide 169 a,b yu sing iridium catalystw ith (S)-H 8 -BINAP as al igand, to yield oxindole 170 a bearing at ertiary alcohol in 69 %y ield and 72 % ee [Scheme49, Eq. (1)].S ubsequently,Y amamoto and co-workers [72] expanded the scope of this reactionw ith N,N-dimethyl carbamoyl as ad irecting group by using iridium catalyst and ab identate phosphoramidite ligand 172.Avariety of aromatic and aliphatic a-ketoamidesw erei nvestigated to afford the desired 3-hydroxy-2-oxindoles 170 b in 69-99 %y ield and 80-99 % ee [Scheme 49, Eq. (2)].…”

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

“…Recently, iridium has emerged as a powerful catalyst for C–H bond functionalization [ 20 – 23 ]. In 2014, Yamamoto and co-workers reported a cationic iridium complex catalyzed asymmetric intramolecular hydroarylation of α-ketoamides, yielding 3-substituted 3-hydroxy-2-oxindoles with high regioselectivities and enantioselectivities (up to 98% ee, Scheme 7 ) [ 24 ]. The reactions were performed in 1,2-dimethoxyethane using 5 mol % of [Ir(cod) 2 ](BAr F 4 ) as the catalyst and 5.5 mol % of the chiral ligand L4 .…”

Rh(III)‐Catalyzed Ring‐Opening Addition of Azabenzonorbornadienes with Cyclic N‐Sulfonyl Ketimines via C−H Bond Activation

“…Among them, the directing group strategy has been widely applied, which not only has improved the reactivity of CÀ H bond, but also left a useful handle for the further elaboration of the products. In the past decade, the direct additions of arenes to multiple bonds such as C=O, [3] C=N, [4] and C=C [5] were extensively studied. Various directing groups (DG) were employed to activate the substrates and allow the regioselective additions.…”