Asymmetric Nazarov Cyclizations Catalyzed by Chiral-at-Metal Complexes

作者：Mietke Thomas; Cruchter Thomas; Larionov Vladimir A; Faber Tabea; Harms Klaus; Meggers Eric^*

来源：Advanced Synthesis & Catalysis, 2018, 360(11): 2093-2100.

DOI：10.1002/adsc.201701546

• Nazarov cyclization
• chiral Lewis acid
• asymmetric catalysis
• chiral-at-metal
• iridium
• rhodium

The application of Lewis acidic chiral-at-metal complexes of iridium(III) and rhodium(III) as catalysts for the asymmetric polarized Nazarov cyclization of dihydropyran- and indole-functionalized alpha-unsaturated beta-ketoesters is reported (overall 24 examples). For both substrate classes, catalyst loadings of 2mol% were found to be sufficient for achieving high yields and high stereoselectivities. The cyclized dihydropyran products were isolated in 85-98% yield, with 89%- > 99%ee, and trans/cis ratios of 15:1-50:1 (9 examples). The cyclized indole products were typically isolated in more than 70% yield and in up to 93% yield, typically with more than 90%ee and in up to 97%ee, and trans/cis ratios of 12:1-28:1 (15 examples).

• 出版日期2018-6-5