1,6-Dihydro-1,6-disilapentalene derivatives by 1,1-organoboration of triynes

Metallacyclopentadienes and related heterocycles via 1,1‐organoboration of alkyn‐1‐ylmetal compounds

“…The polyynes with terminal hydrogen (60,61) react with triethylborane in boiling toluene. However, complex mixtures are formed in both cases [77,78]; this can be understood considering the results of the 1,1-ethylboration of diethynyl(dimethyl)silane [59].…”

“…The kinetic stability of Si C bonds invites for the synthesis of triynes [77] or tetraynes [78], where the C C bonds are separated by two or more SiMe 2 units (or SiMe 2 and SnMe 2 units), SCHEME 26 A silacyclopentadiene with three Si-H functions; loss of stereoselectivity as a result of electron-deficient Si-H-B bridges.…”

“…In contrast, the reaction of the triyne 62 with triorganoboranes is almost selective, leading to 1,6-dihydro-1,6-disilapentalene derivatives 67 (SiMe 3 ) together with small amounts of the silole 68 which is the result of the initial attack at the central Si C C Si unit [77]. The formation of 1,6-dihydro-1,6-disilapentalene derivatives 67 (SnMe 3 ) is highly selective, since the Sn C are much more reactive than Si C bonds toward triorganoboranes [77] (Scheme 28).…”

Fused Silacarbacycles Containing a Silole Unit: 1,2‐Hydroboration and 1,1‐Organoboration of Alkynyl(vinyl)silanes

“…[15] [26] and in some cases by gradient-enhanced 1 H-1 H NOE difference experiments. [27] EI-MS spectra: Finnigan MAT 8500 spectrometer (ionisation energy 70 eV) with direct inlet, the m/z data refer to the isotopes 1 H, 12 C, 11 B, 14 N, 28 Si. Elemental analyses were performed with a Vario Elementar EL III.…”

“…[9,10] This includes even functional groups such as hydrogen and/or chlorine at silicon. [11] Previously, we have shown that 1,1-organoboration of certain triynes affords mainly 1,6-dihydro-1,6-disilapentalene derivatives [12] (Scheme 1), along with side products, which could not be separated. Similar results were obtained with comparable tetraynes.…”