Silylene and Disilene Additions to an Octa-1,3,5,7-tetrayne:  Formation of a C−C-Linked Quatersilirene^1,2

Abstract

Tetra-tert-butyldisilene and di-tert-butylsilylene (1), generated by photolysis of hexa-tert-butylcyclotrisilane, react with 1,8-di-tert-butylocta-1,3,5,7-tetrayne to furnish a C−C-linked bis(disilacyclobutene) derivative with terminal alkynyl groups 7 and a quatersilirene 8 by addition of 1 to all C−C triple bonds. Upon prolonged irradiation, 8 rearranges partly to the 2,5-disilabicyclo[2.2.0]hexa-1(6),3-diene with terminal silirene groups 9. The structures of 7, 8, and 9 were determined by X-ray crystallography.

Reactions of Silylenes with Acetylenes and 1,3-Diacetylenes Linked by C−C Multiple-Bond Units1,2

“…Thus, the 13 C NMR spectrum contained only signals for olefinic skeletal carbon atoms. The 29 Si NMR spectrum is more informative, showing two deshielded signals at 36.70 and 38.99 ppm, in the same range as those for bicyclic systems of the type 5 (Scheme ). , …”

“…The analytical and spectral data indicate the formations of the bis(silirene) 7 with an olefinic double-bond linkage. Of high diagnostic value are the 13 C NMR spectrum, showing only signals for olefinic carbon atoms in the low-field part of the spectrum, and the 29 Si NMR spectrum, exhibiting only a high-field signal at −71.88 ppm in the typical range for silirenes with this substitution pattern ,,, (Scheme ).…”

“…We recently even obtained a quatersilirene by cycloaddition of four molecules of 2 to a 1,3,5,7-tetrayne. This product is also thermally stable but, similar to 4 , undergoes rearrangement upon longer photolysis 1 …”

Reactivity of Polyynes: Complex Molecules from Simple Carbon Rods

“…[85] As a result, a mixture of C-C-linked bis(disilacyclobutene) derivative with terminal alkynyl groups 152 and a quatersilirene 153 were obtained. However, Weidenbruch and co-workers reported the reaction of 1,8-ditert-butyloctatetrayne 150 with products of in situ photolysis of hexa-tert-butylcyclotrisilane (151), tetra-tert-butyldisilene and di-tert-butylsilylene (Scheme 10).…”

“…However, Weidenbruch and co-workers reported the reaction of 1,8-ditert-butyloctatetrayne 150 with products of in situ photolysis of hexa-tert-butylcyclotrisilane (151), tetra-tert-butyldisilene and di-tert-butylsilylene (Scheme 10). [85] As a result, a mixture of C-C-linked bis(disilacyclobutene) derivative with terminal alkynyl groups 152 and a quatersilirene 153 were obtained. Upon longer UV-light irradiation 153 partly rearranges to the 2,5-disilabicyclo[2.2.0]hexa-1(6),3-diene 154 with terminalsilirene group.…”