10.1002/anie.201810714
Angewandte Chemie International Edition
COMMUNICATION
alkylboronic acids, synthetically valuable alternatives to the
corresponding esters. Moreover, alkylboronic acids are of
interest in pharmaceutical science as borono-bioisosters of
carboxylic acids.[19] Treatment with KHF2 converted alkyl
boronate ester 3ak to the corresponding organotrifluoroborate 7.
The stereospecific coupling of 3-borylated perhydroindole
derivative 3al with lithiated furan and 3-fluoropyridine was
performed in order to demonstrate the synthetic utility of the
obtained products.[20] However, the coupling with lithiated 3-
Conflict of interests
The authors declare no conflict of interest.
Keywords: arene hydrogenation • boronic esters • cycloalkanes
• heterocycles • building blocks
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Scheme 4. Hydrogenation of aryltrifluoroborates and photocatalytic
transformation.
Photocatalyst
(PC) = [Ir(dFCF3ppy)2bpy][PF6],
DME = dimethoxyethane, dtbbpy = 4,4’-di-tert-butyl-2,2’-dipyridyl. [a] The
product contained traces of an unknown impurity. [b] The d.r. value was
determined by 1H NMR.
In conclusion, we have developed a straightforward method
to access borylated carbo- and heterocycles from readily
available aryl boronic acids and their derivatives by Rh–CAAC
catalyzed[13] arene hydrogenation. The cyclic alkylboron building
blocks, which were previously difficult to access, were generally
obtained in very high yields, with high diastereoselectivity and
tolerating a broad variety of functional groups. Overall, we hope
that this approach and the products described herein, will be
widely used to enable a number of material science, drug design
and agrochemical applications.
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Acknowledgements
Generous
financial
support
by
the
Deutsche
Forschungsgemeinschaft (IRTG 2027) and the Fonds der
Chemischen Industrie (D.M.) is gratefully acknowledged. We are
grateful to Jonas Luca Schwarz and Arne Heusler for skillful
technical assistance. We thank Mario P. Wiesenfeldt, Dr.
Zackaria Nairoukh, and Dr. Michael J. James for helpful
discussions. We also thank Dr. Constantin G. Daniliuc for X-ray
crystallographic analysis.
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catalyst system indicate similar conclusions. A thorough mechanistic
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