A B C
Z. Naturforsch. 2013, 68b, 666 – 674
doi:10.5560/ZNB.2013-3088
Facile 1,1-Carboboration Reaction of a Diarylphosphino-substituted Conjugated Diyne with Tris(pentafluorophenyl)borane
Philipp Feldhaus, Gerald Kehr, Roland Fröhlich$, Constantin G. Daniliuc$, and Gerhard Erker
Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149 Münster, Germany
$ X-Ray crystal structure analyses
Reprint requests to Prof. Dr. Gerhard Erker. Fax: +49 251 83 36503. E-mail: erker@uni-muenster.de
Received March 15, 2013 / published online Juli 2, 2013
Dedicated to Professor Heinrich Nöth on the occasion of his 85th birthday
Bis(dimesitylphosphanyl)butadiyne (14) reacts with B(C6F5)3 by a 1,1-carboboration sequence. The selective attack at a single phosphanyl-alkyne moiety is observed. First a phosphirenium-borate zwitterion 15 is formed at r. t. Thermolysis (80 °C) results in the E-selective formation of the 1,1-carboboration product, the frustrated Lewis pair (FLP) E-16, which upon heating to 160 °C eventually undergoes isomerization followed by an internal nucleophilic aromatic substitution reaction to give the product 17 featuring a -B(F)(C6F5)2 substituent at the five-membered P-heterocycle. Finally, the FLP E-16 was reacted with n-butylisocyanide to yield the five-membered heterocyclic product 18, formed by P,B addition to the isonitrile carbon atom. Compounds 14, 15, 17, and 18 were characterized by X-ray crystal structure analyses.
Key words: Carboboration, Boron, Phosphorus, Frustrated Lewis Pair
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