Tricyclo[2.1.0.02,5]pentane and its derivatives

Pentasilatricyclo[2.1.0.02,5]pentane and Its Anion

“…[7] One should mention that no stable representatives of tricyclo[2.1.0.0 2,5 ]pentanide derivatives are known in organic chemistry. [1,4] As expected, the anionic bridgehead silicon in 3 À ·K + was more shielded than that in the neutral precursor 2, being observed at the very high field of À253.9 ppm. [9] In the crystalline form, potassium pentasilatricyclo[2.1.0.0 2,5 ]pentan-1-ide exists as a contact ion pair, in which potassium lacks coordination to a nucleophilic solvent.…”

“…[13] It is interesting to note that although the R 3 Si(Ph)Si bridge in 3 À ·K + fixes a very acute interplanar angle Si3-Si1-Si2/Si4-Si1-Si2 of 93.45(10)8, the bridging Si1 À Si2 bond of 2.3801(6) is quite normal, in contrast to typical tricyclo[2.1.0.0 2,5 ]pentanes featuring extremely short CÀC bridges. [1,4] This again should be ascribed to the presence of an anionic center at the bridgehead Si1 and the resulting high p-character of the Si1 À Si2 bridge bond (Si1A C H T U N G T R E N N U N G (sp 7.4 )-Si2-A C H T U N G T R E N N U N G (sp 6.6 )).…”

Nonconjugated Hydrocarbons as Rigid‐Linear Motifs: Isosteres for Material Sciences and Bioorganic and Medicinal Chemistry

“…Naturally, there are more compounds that fulfill the requirements of this Review article, such as the rigid‐linear hydrocarbons tricyclo[2.1.0.0 2, 5 ]pentane 338 , dodecahedrane 339 , and trishomocubane 340 (Figure ). Although, in the case of tricyclo[2.1.0.0 2, 5 ]pentane, while it satisfies the criteria for this review, the stability of the plain hydrocarbon is too low to be of practical use . Similarly, dodecahedrane has great potential to be used as a linear linker, although its 23 step synthesis and its size limit its applicability in many of the areas outlined.…”

“…Naturally,t here are more compounds that fulfill the requirementso ft his Review article, such as the rigid-linear hydrocar- [447] 338,d odecahedrane [448] 339, and trishomocubane [449] 340 (Figure 82). Although, in the case of tricyclo[2.1.0.0 2, 5 ]pentane, while it satisfies the criteria for this review,t he stabilityo ft he plain hydrocarbon is too low to be of practical use.…”

MCSCF study of the thermal isomerization of tricyclo[2.1.0.02,5]pentane to 1,3‐cyclopentadiene

“…T ricyclo[2.1.0.0 2,5 ]pentane (1) is the smallest in a series of rigidly fixed bicyclobutanes [1]. It was first characterized by Andrews and Baldwin [2], who found a mixture of 1 and bicyclo[2.1.0]pent-2-ene resulting from the photolysis of 1,3-cyclopentadiene (2).…”