3-Trimethylsilylcyclobutylidene. The γ-Effect of Silicon on Carbenes
作者:Xavier Creary
DOI:10.1021/ja400747u
日期:2013.5.1
was generated by pyrolysis of the sodium salt of the tosylhydrazone derivative of 3-trimethylsilylcyclobutanone. This carbene converts to 1-trimethylsilylbicyclobutane as the major product. A labeling study shows that this intramolecular rearrangement product comes from 1,3-hydrogen migration to the carbenic center and not 1,3-silyl migration. Computational studies show two carbene minimum energy conformations
group 14 elements at the 3-position were synthesized, and their thermal ring-opening reactions were studied. Carbon-substituted cyclobutene underwent the ring-opening reaction through an outward pathway to afford the E-diene exclusively. On the other hand, the ring-opening reaction of the silyl, germyl, and stannyl substituted cyclobutenes occurred in both outward and inward directions giving a mixture
Cycloalkane and Cycloalkene C−H Bond Dissociation Energies
作者:Zhixin Tian、Alireza Fattahi、Lev Lis、Steven R. Kass
DOI:10.1021/ja065348u
日期:2006.12.1
Both C-Hbond dissociation energies for cyclobutene were measured in the gas phase (BDE = 91.2 +/- 2.3 (allyl) and 112.5 +/- 2.5 (vinyl) kcal mol-1) via a thermodynamic cycle by carrying out proton affinity and electron-binding energy measurements on 1- and 3-cyclobutenyl anions. The results were compared to those for an acyclic model compound, cis-2-butene, and provide the needed information to experimentally