B. Wrackmeyer, H. Maisel, W. Milius
Jun 1, 2003
Citations
0
Influential Citations
5
Citations
Journal
Zeitschrift für Naturforschung B
Abstract
The hydroboration of bis(trimethylsilylethynyl)silanes Me(R)Si(C CÐSiMe3)2 1a (R = Me) and 1b (R = H) with 9-borabicyclo[3.3.1]nonane (9-BBN) does not give products related to the usual cis-1,2-hydroboration of one or both C C bonds. Instead, the major products obtained from 1a are the two isomers of 2,5-bis(trimethylsilyl)-2,5-bis[9-(9-borabicyclo[3.3.1]nonyl)]-1-sila-3-cyclopentene 2a and 2a (silolenes), and from the reaction of 1b with 9-BBN solely the silolene 2b can be isolated. The silolenes 2a and 2b were studied by X-ray structural analysis. The reaction of 1a with 9-BBN in a 1:1 molar ratio gave a mixture of products, consisting of the silolenes 2a and 2a , some unidentified material, and 2,5-bis(trimethylsilyl)3-[9-(9-borabicyclo[3.3.1]nonyl)]-1-sila-2,4-cyclopentadiene 3a. The silole 3a was then prepared in pure state by the reaction of 1a with 9-isobutyl-9-borabicyclo[3.3.1]nonane in boiling toluene, where the borane decomposes slowly into isobutene and 9-BBN which is trapped by 1a. The proposed structures of the heterocycles 2 and 3 in solution follow from a consistent set of NMR data (1H, 11B, 13C, 29Si NMR).