5617-70-9Relevant articles and documents
Cyclopropylidenemethanone: A Quasi-Symmetrical Molecule
Brown, Ronald D.,Godfrey, Peter D.,Kleiboemer, Burkhard,Champion, Robert,Elmes, Patricia S.
, p. 7715 - 7718 (1984)
The structure of cyclopropylidenemethanone has been investigated via microwave spectroscopy.Analysis of the spectra of the ground and nine excited vibrational states has revealed the form of two bending potentials involving motion of the methanone group relative to the cyclopropylidene ring.The vibration perpendicular to the plane containing the ring carbon atoms has a double-minimum potential with the ground state lying just 2 cm-1 below the 29 cm-1 high central barrier.Analysis of this motion using the rigid bender method shows that the two potential minima lie 17.5 deg away from the ring plane.The proximity of the ground state to the top of the barrier leads to the designation of the molecule as quasi-symmetric, being close to C2ν, despite its less symmetric Cs equilibrium structure.The vibration in the plane of the ring has a near harmonic potential, with a fundamental of 154 cm-1.Analysis of the Stark effect indicates a dipole moment of 2.60(1) D.
Inherent Reactivity of Spiro-Activated Electrophilic Cyclopropanes
Jüstel, Patrick M.,Ofial, Armin R.,Pignot, Cedric D.,Stan, Alexandra
supporting information, p. 15928 - 15935 (2021/10/25)
The kinetics of the ring-opening reactions of thiophenolates with geminal bis(acceptor)-substituted cyclopropanes in DMSO at 20 °C was monitored by photometric methods. The determined second-order rate constants of the SN2 reactions followed linear relationships with Mayr nucleophilicity parameters (N/sN) and Br?nsted basicities (pKaH) of the thiophenolates as well as with Hammett substituent parameters (σ) for groups attached to the thiophenolates. Phenyl-substituted cyclopropanes reacted by up to a factor of 15 faster than their unsubstituted analogues, in accord with the known activating effect of adjacent π-systems in SN2 reactions. Variation of the electronic properties of substituents at the phenyl groups of the cyclopropanes gave rise to parabolic Hammett relationships. Thus, the inherent SN2 reactivity of electrophilic cyclopropanes is activated by electron-rich π-systems because of the more advanced C1?C2 bond polarization in the transition state. On the other hand, electron-poor π-systems also lower the energetic barriers for the attack of anionic nucleophiles owing to attractive electrostatic interactions.
An efficient method for the synthesis of 2′,3′-nonsubstituted cycloalkane-1,3-dione-2-spirocyclopropanes using (2-bromoethyl)-diphenylsulfonium trifluoromethanesulfonate
Nambu, Hisanori,Ono, Naoki,Hirota, Wataru,Fukumoto, Masahiro,Yakura, Takayuki
, p. 1763 - 1768 (2016/12/09)
An efficient and practical synthesis of 2′,3′-nonsubstituted cyclohexane-1,3-dione-2-spirocyclopropanes using a sulfonium salt was achieved. The reaction of 1,3-cyclohexanediones and (2-bromoethyl)diphenylsulfonium trifluoromethanesulfonate with powdered K2CO3 in EtOAc at room temperature (r.t.) provided the corresponding spirocyclopropanes in high yields. The synthetic method was also applied to 1,3-cyclopentanedione, 1,3-cycloheptanedione, 1,3-indanedione, acyclic 1,3-diones, ethyl acetoacetate, and Meldrum's acid.
