TY - JOUR
T1 - α,β-Unsaturated Amides as Dipolarophiles
T2 - Catalytic Asymmetric exo-Selective 1,3-Dipolar Cycloaddition with Nitrones
AU - Zhang, Ming
AU - Kumagai, Naoya
AU - Shibasaki, Masakatsu
N1 - Funding Information:
This work was financially supported by ACT-C (JPMJCR12YO) from JST, and KAKENHI (25713002, 17H03025, and JP16H01043 in Precisely Designed Catalysts with Customized Scaffolding) from JSPS and MEXT. NK thanks The Naito Foundation for financial support. Dr. Tomoyuki Kimura is gratefully acknowledged for the X-ray crystallographic analysis. We thank Dr. Ryuichi Sawa, Ms. Yumiko Kubota, and Dr. Kiyoko Iijima for the NOE & DOSY analyses.
Publisher Copyright:
© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2017/9/12
Y1 - 2017/9/12
N2 - 1,3-Dipolar cycloaddition is a commonly exploited method to access 5-membered chemical entities with a variety of peripheral functionalities and their stereochemical arrangements. Nitrones are isolable 1,3-dipoles that exhibit sufficient reactivity toward electron-deficient olefins in the presence of Lewis acids to deliver highly substituted isoxazolidines. Herein we document that α,β-unsaturated amides, generally regarded as barely reactive in a 1,3-dipolar reaction manifold, were effectively activated using the designed 7-azaindoline auxiliary in an In(OTf)3/bishydroxamic acid catalytic system. The broad substrate scope and clean removal of the 7-azaindoline auxiliary from the product highlight the synthetic utility of the present catalysis.
AB - 1,3-Dipolar cycloaddition is a commonly exploited method to access 5-membered chemical entities with a variety of peripheral functionalities and their stereochemical arrangements. Nitrones are isolable 1,3-dipoles that exhibit sufficient reactivity toward electron-deficient olefins in the presence of Lewis acids to deliver highly substituted isoxazolidines. Herein we document that α,β-unsaturated amides, generally regarded as barely reactive in a 1,3-dipolar reaction manifold, were effectively activated using the designed 7-azaindoline auxiliary in an In(OTf)3/bishydroxamic acid catalytic system. The broad substrate scope and clean removal of the 7-azaindoline auxiliary from the product highlight the synthetic utility of the present catalysis.
KW - asymmetric catalysis
KW - bishydroxamic acid
KW - cycloaddition reactions
KW - indium
KW - isoxazolidine
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U2 - 10.1002/chem.201702330
DO - 10.1002/chem.201702330
M3 - Article
C2 - 28594065
AN - SCOPUS:85021825319
VL - 23
SP - 12450
EP - 12455
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
SN - 0947-6539
IS - 51
ER -