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Observation of Borane–Olefin Proximity Interaction Governing the Structure and Reactivity of Boron‐Containing Macrocycles
Author(s) -
Murata Yukihiro,
Matsunagi Kenta,
Kashida Junki,
Shoji Yoshiaki,
Özen Cihan,
Maeda Satoshi,
Fukushima Takanori
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202103512
Subject(s) - borane , boranes , chemistry , intramolecular force , moiety , olefin fiber , frustrated lewis pair , alkyne , reactivity (psychology) , boron , van der waals force , hydroboration , computational chemistry , ammonia borane , photochemistry , stereochemistry , molecule , organic chemistry , lewis acids and bases , catalysis , dehydrogenation , medicine , alternative medicine , pathology
While attractive interactions between borane and olefin have been postulated to trigger various boron‐mediated organic transformations, proximity structures of these functional groups, other than the formation of weak van der Waals complexes, have never been directly observed. Here we show that a close intramolecular borane–olefin interaction operates in macrocyclic systems containing borane and olefinic groups obtained by multi‐step 1,2‐carboboration between a strained alkyne and 9‐borafluorene derivatives. Depending on Lewis acidity of the borane moiety and the size of the macrocycles, the magnitude of interaction changes, resulting in different reaction modes. The whole picture of the multi‐step reactions has been revealed experimentally with theoretical supports. The present finding may not only provide a deeper understanding of the fundamental boron‐mediated interaction but also lead to the development of new organic transformations involving molecular activation by boranes.