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Asymmetric Nazarov Cyclizations Catalyzed by Chiral‐at‐Metal Complexes
Author(s) -
Mietke Thomas,
Cruchter Thomas,
Larionov Vladimir A.,
Faber Tabea,
Harms Klaus,
Meggers Eric
Publication year - 2018
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201701546
Subject(s) - chemistry , dihydropyran , yield (engineering) , catalysis , indole test , iridium , rhodium , lewis acids and bases , metal , substrate (aquarium) , enantioselective synthesis , medicinal chemistry , organic chemistry , stereochemistry , materials science , oceanography , metallurgy , geology
Abstract 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 α‐unsaturated β‐ketoesters is reported (overall 24 examples). For both substrate classes, catalyst loadings of 2 mol% 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).