Volume 8 Issue 3
Synthesis, Characterisation and Reactions of Phosphine-Substituted Alkynylboronates and Alkynyltrifluoroborate Salts
Jérôme F. Vivat, Sylvestre P. J. T. Bachollet, Harry Adams and Joseph P. A. Harrity
Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK
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Abstract
The synthesis and structural characterisation of phosphine-substituted alkynylboronates is reported. A P(III)-centred alkynylboronate (2) was prepared that showed little evidence for the conjugation of the P-lone pair to the boron via the alkyne π-system, as judged by X-ray crystallography studies of 2 and a related P(V) compound, 3. In addition, corresponding alkynyltrifluoroborate salts were prepared that showed improved stability by comparison to their boronic ester counterparts. These salts undergo Pd-catalysed cross-coupling reactions with aryl halides.
Keywords:alkynylboronate; trifluoroborate salt; conjugation; phosphine; cross-coupling