Categories: C-C Bond Formation > Cyclic compounds > Cycloalkenes
Synthesis of cyclopropenes
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Recent Literature
A novel Rh(II)-catalyzed enantioselective [2 + 1]-cycloaddition of ethyl
diazoacetate to terminal acetylenes and olefins with high enantioselectivity is
described. The catalyst, which is readily available, robust, and effective, can
be recovered and reused.
Y. Lou, M. Horikawa, R. A. Kloster, N. A. Hawryluk, E. J. Corey, J. Am. Chem.
Soc., 2004, 126, 8916-8918.
Dianions generated from alkyllithium reagents and cycloprop-2-ene carboxylic
acids can be functionalized by electrophiles at the vinylic position. Due to
reproducibility issues for reactions that were carried out in Et2O, a
detailed study revealed that THF was a superior solvent. Additionally, it was
found that the addition of NMO has a beneficial effect both on the stability of
the dianions and on the rates of alkylation.
L. A. Fisher, J. M. Fox, J. Org. Chem., 2008,
73, 8474-8478.
A new cyclopropenation reaction, which involves Cα-Si bond insertion of
alkylidene carbenes derived from α-silyl ketones, features excellent selectivity
for insertion into Cα-Si bonds rather than insertion into Cγ-H bonds or addition
to γ,δ-double or -triple bonds. The selectivity trend clearly indicates that the
α-oxygen in the tether significantly promotes Cγ-H insertion.
J. Li, C. Sun, D. Lee, J. Am. Chem. Soc., 2010,
132, 6640-6641.
Sodium bromodifluoroacetate (BrCF2CO2Na) is an effective
difluorocarbene source for high-yielding synthesis of gem-difluorocyclopropanes
and gem-difluorocyclopropenes under mild conditions.
K. Oshiro, Y. Morimoto, H. Amii, Synthesis, 2010,
2080-2084.
