No abstract

The reactions of tert-butyl-, sec-butyl-, and n-butyllithium with vinyldimethylfluorosilane include addition to the double bond giving silene and/or silenoid intermediates, fluorine substitution, and an unprecedented vinyl substitution. For the tert-butyllithium reaction product stereochemistry and trapping experiments using both cyclopentadiene and methoxytrimethykilane show that silenes are not formed in tetrahydrofuran and that in hexane about 67% of the 1,3-disilacyclobutanes obtained arise from silene dimerization while 33% are formed by silenoid coupling. In hexane the order of reactivity for addition t-Bu > sec-Bu > n-Bu is opposite that for fluorine substitution. The vinyl substitution reaction is most significant for secondary alkyllithium reagents including the tert-butyllithium adduct to vinyldimethylfluorosilane, 3 (X = F), and sec-butyllithium. Evidence for the formation of vinyllithium or ethylene in the process could not be obtained.

Die Reaktion von tBu‐ Li (I) mit verschiedenen Mengen der Titelverbindung (I) in Hexan bzw. THF liefert die Produkte (‐III) und (IV).

Die E‐ und Z‐Isomeren von l‐Phenyl‐1‐methyl‐2‐neopentylsilen, die durch Reaktion von (I) mit BuLi bei tiefen Temp. erzeugt werden, werden stereospezifisch durch Trimethylmethoxysilan unter Bildung einer Mischung von (IIA) und (IIB) abgefangen.