Azaborabutadienes: Synthesis by Metal-Free Carboboration of Nitriles and Utility as Building Blocks for B,N-Heterocycles

Metal‐free regioselective carboboration of arylnitriles with L2PhB: (1: L=oxazol‐2‐ylidene) catalyzed by Et3B afforded the unprecedented acyclic 2‐aza‐4‐borabutadienes 2, thus demonstrating a new strategy to construct a B,C,N‐mixed π‐system involving B=C and C=N bonds. Thermal isomerization of 2 gav...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2016-11, Vol.55 (47), p.14718-14722
Main Authors: Kong, Lingbing, Lu, Wei, Li, Yongxin, Ganguly, Rakesh, Kinjo, Rei
Format: Article
Language:English
Subjects:
Bonding
Boron
carboboration
Construction
Cyanide
heterocycles
Hydrogen
Isomerization
Metals
multiple bonds
Nitriles
Oxazol
structure elucidation
Substrates
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Summary:Metal‐free regioselective carboboration of arylnitriles with L2PhB: (1: L=oxazol‐2‐ylidene) catalyzed by Et3B afforded the unprecedented acyclic 2‐aza‐4‐borabutadienes 2, thus demonstrating a new strategy to construct a B,C,N‐mixed π‐system involving B=C and C=N bonds. Thermal isomerization of 2 gave C‐borylimines (3), and diverse reactivity of 2 a towards several substrates, such as H+, F+, O2, S, Se, and isonitriles, allowed construction of boron‐containing heterocycles with various ring sizes, thus illustrating the utility of 2 as a synthetic building block. Metal‐free regioselective carboboration of arylnitriles with L2PhB: 1 (L=oxazol‐2‐ylidene) afforded the acyclic 2‐aza‐4‐borabutadienes 2 a–c. Thermal isomerization of 2 a–c gave C‐borylimines while reactions of 2 a towards several substrates allowed construction of B,N‐containing heterocycles with various ring sizes (three‐ to six‐membered rings), thus demonstrating the synthetic utility of 2 as building blocks.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201608994