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Metal‐Free Acetylene Coupling by the (C 6 F 5 ) 2 B−X 1,2‐Halogenoboration Reaction
Author(s) -
Ueno Atsushi,
Li Jun,
Daniliuc Constantin G.,
Kehr Gerald,
Erker Gerhard
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201802084
Subject(s) - alkyne , chemistry , acetylene , adduct , pyridine , metal , coupling reaction , x ray crystallography , halide , crystallography , medicinal chemistry , stereochemistry , diffraction , organic chemistry , physics , catalysis , optics
(C 6 F 5 ) 2 B‐halides were conveniently prepared by treatment of (C 6 F 5 ) 2 BH with tritylchloride or ‐bromide, respectively. With cyclopropylacetylene, (C 6 F 5 ) 2 BBr underwent sequential cis ‐1,2‐halogenoboration followed by 1,2‐carboboration to give the 4‐bromo‐2,4‐dicyclopropylbutadienyl‐B(C 6 F 5 ) 2 product. It reacted further with additional cyclopropylacetylene to give the linear triene and tetraene products in a metal‐free alkyne oligomerization reaction. The pyridine adduct of the initial diene product was characterized by X‐ray diffraction. (C 6 F 5 ) 2 BCl reacted analogously. Similar (C 6 F 5 ) 2 BX induced oligomerization reactions were carried out with two conjugated enynes.