Cobalt‐Catalyzed Asymmetric Sequential Hydroboration/Isomerization/Hydroboration of 2‐Aryl Vinylcyclopropanes

A cobalt‐catalyzed asymmetric sequential hydroboration/isomerization/hydroboration of 2‐aryl vinylcyclopropanes was for the first time reported for the preparation of valuable chiral 1,5‐bis(boronates) in good yields with excellent enantioselectivity via asymmetric sequential isomerization/hydrobora...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2022-07, Vol.61 (30), p.n/a
Main Authors: Chen, Chenhui, Wang, Hongliang, Li, Tongtong, Lu, Dongpo, Li, Jiajing, Zhang, Xie, Hong, Xin, Lu, Zhan
Format: Article
Language:English
Subjects:
Alkanes
Aromatic compounds
Asymmetry
Chemical reactions
Chiral Boronates
Cobalt
Computer applications
Cross coupling
Enantiomers
Hydroboration
Isomerization
Iterative Coupling
Iterative methods
Vinylcyclopropanes
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Summary:A cobalt‐catalyzed asymmetric sequential hydroboration/isomerization/hydroboration of 2‐aryl vinylcyclopropanes was for the first time reported for the preparation of valuable chiral 1,5‐bis(boronates) in good yields with excellent enantioselectivity via asymmetric sequential isomerization/hydroboration of a trisubstituted alkene intermediate. The reaction was carried out smoothly and this protocol was used for asymmetric syntheses of (−)‐preclamol in gram‐scale. The two primary C(sp3)−B bonds in chiral 1,5‐bis(boronates) could be distinguished in iterative Suzuki–Miyaura cross‐coupling reaction, delivering chiral 1,2,5‐triaryl alkanes with excellent enantioselectivity. Based on experimental and computational studies, a cobalt‐hydride species was proposed as the active intermediate in hydroboration, isomerization, and second hydroboration reactions. Chiral 1,5‐bis(boronates) were synthesized via an enantioselective cobalt‐catalyzed sequential hydroboration/isomerization/hydroboration of vinylcyclopropanes through a trisubstituted alkene intermediate. These chiral 1,5‐bis(boronates) were further converted into chiral 1,2,5‐triaryl alkanes by an iterative Suzuki–Miyaura cross‐coupling reaction with aryl halides.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202205619