Asymmetric Nazarov Cyclizations Catalyzed by Chiral-at-Metal Complexes
Asymmetric Nazarov Cyclizations Catalyzed by Chiral-at-Metal Complexes
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DOI：
10.1002/adsc.201701546
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发表时间：
2018-06-05
影响因子：
5.4
通讯作者：
Meggers，Eric
中科院分区：
文献类型：
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作者：
Mietke，Thomas;Cruchter，Thomas;Meggers，Eric
报道了铱（III）和铑（III）的刘易斯酸性手性金属络合物作为催化剂用于二氢吡喃-和吲哚-官能化的α-不饱和β-酮酯的不对称极化Nazarov环化的应用（总共24个实施例）。对于两种底物类别，发现2摩尔%的催化剂负载量足以实现高产率和高立体选择性。 环化的二氢吡喃产物以85-98%的产率分离，具有89%-> 99%ee，并且反式/顺式比率为15：1-50：1（9个实施例）。 环化的吲哚产物通常以大于70%的产率和至多93%的产率分离，通常具有大于90%ee和至多97%ee，并且反式/顺式比率为12：1-28：1（15个实施例）。
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, andtrans/cisratios 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, andtrans/cisratios of 12:1–28:1 (15 examples).