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Topics in Current Chemistry (2020) 378:9
The robust relay catalysis also enables asymmetric C(sp2)–H insertion reaction
with arenes. In 2017, Xu et al. [77] reported an asymmetric arylation of α-diazo
esters with anilines catalyzed by an achiral dirhodium(II) complex and a spiroCPA 79 (Scheme 21). Mechanistic studies suggested that a zwitterionic intermediate was generated from the reaction of α-aryl diazoacetate and aniline after
the dissociation of rhodium. The enantioselectivity-determining step was a SPAmediated 1,2-proton shift via a seven-membered proton shuttle transition state.
In 2017, Luo and Gong developed an enantioselective aza-ene-type reaction
of α-diazo esters and enamides 82 under the relay catalysis of XPhosAuNTf 2 and
CPA 83 (Scheme 22) [78]. This cascade reaction was initiated by nucleophilic
Scheme 20 S–H and O–H insertion reaction via rhodium and spiro-CPA relay catalysis
Scheme 21 C–H insertion reaction via rhodium and spiro-CPA relay catalysis
Scheme 22 Enantioselective aza-ene-type reactions of enamides with Au(I) carbenoids
Reprinted from the journal
197
Topics in Current Chemistry (2020) 378:9
The robust relay catalysis also enables asymmetric C(sp2)–H insertion reaction
with arenes. In 2017, Xu et al. [77] reported an asymmetric arylation of α-diazo
esters with anilines catalyzed by an achiral dirhodium(II) complex and a spiroCPA 79 (Scheme 21). Mechanistic studies suggested that a zwitterionic intermediate was generated from the reaction of α-aryl diazoacetate and aniline after
the dissociation of rhodium. The enantioselectivity-determining step was a SPAmediated 1,2-proton shift via a seven-membered proton shuttle transition state.
In 2017, Luo and Gong developed an enantioselective aza-ene-type reaction
of α-diazo esters and enamides 82 under the relay catalysis of XPhosAuNTf 2 and
CPA 83 (Scheme 22) [78]. This cascade reaction was initiated by nucleophilic
Scheme 20 S–H and O–H insertion reaction via rhodium and spiro-CPA relay catalysis
Scheme 21 C–H insertion reaction via rhodium and spiro-CPA relay catalysis
Scheme 22 Enantioselective aza-ene-type reactions of enamides with Au(I) carbenoids
Reprinted from the journal
197