Gary T. Burns

Generation and trapping of 6,6-dimethyl-6-silafulvene

Abstract Flow pyrolysis of allylcyclopentadienyldimethylsilane and of 1-dimethylmethoxysilyl-1-trimethylsilylcyclopentadiene afforded 6, 6-dimethyl-6-silafulvene which was either trapped or allowed to dimerize.

1,1-Dimethylsilole☆

Abstract Flash vacuum pyrolysis of 5-benzoyloxy-3,3-dimethyl-3-silacyclopentene afforded 5,5-dimethyl-5-silacyclopentadiene (1,1-dimethylsilole). Although the silole dimerizes at or below room temperature, it could be both trapped with maleic anhydride, and characterized by low-temperature NMR. The silole could also be generated from a thermally-induced retro Dielsue5f8Alder reaction of its dimer.

A novel synthesis of a C-unsubstituted silole

Abstract Flow pyrolysis of 4-allyl-4-methyl-4-silacyclopentene yielded the Diels—Alder dimers of 5-methyl-5-silacyclopentadiene (1-methylsilole) via sequential retro- ene extrusion of propene, 1,5-hydrogen migration to silicon, and dimerization. The monomeric silole is thermally produced in situ, and trapped by maleic anhydride.

Vinylsilylene rearrangement. A possible silacyclopropanylidene intermediate

Abstract It is proposed that trimethylsilylvinylsilylene undergoes sequential rearrangement to a silacyclopropanylidene by silene to silylene isomerization of an intermediate 1-silacyclopropene.

A convenient synthesis of silacyclobutenes

Abstract Flash vacuum pyrolysis of 1,3-bis(trimethylsilyl)-3-methoxysilylpropenes has been found to be an efficient route to silacyclobutenes. The thermolysis is viewed as proceeding through initial β-elimination of trimethylmethoxysilane followed by cyclization of the resulting 1-sila-1,3-butadiene.

The molecular structure of 1-methyl-1-silabicyclo[2.2.2]octatriene as determined by gas phase electron diffraction

Abstract The molecular structure of 1-methyl-1-silabicyclo[2.2.2]octatriene has been determined by gas phase electron diffraction. The molecule was found to exhibit a great deal of angular distortion at the silicon bridgehead while the valence angles at the carbon bridgehead appear to be relatively normal. The observed valence angles at the carbon bridgehead, ∠Cue5fbCue5f8C (119.4(0.7)°) and ∠Cue5f8Cue5f8C (108.3(0.6)°), appear to be unaffected by the ring strain in the molecule. The angles at the silicon bridgehead, ∠Cue5f8Siue5f8C (98.8(0.3)°), ∠Siue5f8Cue5fbC (109.9(0.5)°), and ∠Cmue5f8Siue5f8C (188.7(0.2)°), are very unusual compared with the typical sp3 and sp2 values. These distortions can be qualitatively explained in terms of the relative magnitudes of the bending force constants and in terms of hybridization on the silicon and carbon atoms involved.