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Monobenzofused 1,4‐Azaborines: Synthesis, Characterization, and Discovery of a Unique Coordination Mode
Author(s) -
Xu Senmiao,
Haeffner Fredrik,
Li Bo,
Zakharov Lev N.,
Liu ShihYuan
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201403903
Subject(s) - chemistry , ligand (biochemistry) , metathesis , moiety , stereochemistry , diene , iminium , hydroboration , palladium , enamine , coordination complex , combinatorial chemistry , catalysis , metal , organic chemistry , polymerization , biochemistry , natural rubber , receptor , polymer
We report the first general synthesis of boron‐substituted monobenzofused 1,4‐azaborines using ring‐closing metathesis of an enamine‐containing diene as a key synthetic strategy. As part of our investigations, we discovered that the B‐C3 moiety in a 1,4‐azaborine can serve uniquely as a η 2 ‐L‐type ligand. This functionality is exemplified by two κ 2 ‐ N ‐η 2 ‐BC Pt complexes of a boron‐pyridyl‐substituted monobenzofused‐1,4‐azaborine. Single‐crystal X‐ray diffraction analysis of the Pt complexes shows a strong structural contribution from the iminium resonance form of the monobenzofused‐1,4‐azaborine ligand. We also demonstrate that a palladium(0) complex supported by a 1,4‐azaborine‐based phosphine ligand can catalyze hydroboration of 1‐buten‐3‐yne with unique selectivity. In view of the importance of arene–metal π‐interactions in catalytic applications, this work should open new opportunities for ligand design involving the 1,4‐azaborine motif as an arene substitute.