Reactions of bis(alkynyl)silanes with HB(C6F5)2: Formation of boryl-substituted silacyclobutene derivatives

Treatment of R2Si(CC-SiMe3)2 [1a (Me), 1b (Ph)] with HB(C6F5)2 at low temperature (253 K (a), 273 K (b)) gives the –B(C6F5)2 substituted silacyclobutene products (4a,b) under kinetic control. Upon warming to room temperature they disappear to form the thermodynamically favoured isomeric silole derivatives (2a,b). Similar treatment of Me2Si(CC–R1)2 [5a (R1 = Ph), 5b (R1 = tert-butyl) with HB(C6F5)2 at room temperature gave the stable –B(C6F5)2 substituted silacyclobutene derivatives 6 and 7, respectively. Subsequent photolysis resulted in a Z- to E-isomerization of the substituted exocyclic CC double bonds in these products. The silacyclobutene derivative E-6 was characterized by an X-ray crystal structure analysis.

Graphical abstractBis(alkynyl)silanes react with HB(C6F5)2 under mild conditions to yield the respective –B(C6F5)2 substituted silacyclobutene derivatives.Figure optionsDownload full-size imageDownload as PowerPoint slide