Categories: O-H Bond Formation >
Cleavage of carbonates
Recent Literature
Different from most carbonates the allyloxy carbonyl protecting group can be
cleaved under neutral conditions using expensive precious metals catalysts. Two
new Fe-catalyzed protocols enable a mild liberation of alcohols from
allylcarbonates, broad functional group tolerance, and exclusive
chemoselectivity.
A. P. Dieskau, B. Plietker, Org. Lett., 2011,
13, 5544-5547.
Carbon tetrabromide catalyzes O-tert-butoxycarbonylation of
functionalized phenols without any side reactions (bromination, addition of CBr3
to a double bond, and formation of symmetrical diaryl carbonates, cyclic
carbonates, or carbonic-carbonic anhydrides). The parent phenols are regenerated
from the O-t-Boc derivatives by the catalyst system CBr4-PPh3
without affecting other functional groups.
S. V. Chankeshwara, R. Chebolu, A. K. Chakraborti, J. Org. Chem., 2008,
73, 8615-8618.
The reaction of chiral 1-aminoalkylepoxides with CO2, generated from
acidic treatment of an aqueous solution of NaHCO3 at room temperature,
efficiently afforded enantiopure cyclic carbonates with total selectivity.
Carbonates were readily transformed into the corresponding diols by reaction
with LiAlH4 or by basic hydrolysis.
J. M. Concellón, V. del Solar, S. Carcía-Granda, M. R. Díaz, J. Org. Chem.,
2007,
72, 7567-7568.
An efficient one-pot procedure for the zinc-mediated reduction of nitroarenes
in the presence of chloroformates leads to the corresponding N,O-bisprotected
hydroxylamines in good yield under ambient conditions in THF-water mixtures.
Solvolysis of the bisprotected hydroxylamines with sodium methoxide at room
temperature provides access to synthetically versatile N-aryl-N-hydroxy
carbamates in excellent yields.
A. Porzelle, M. D. Woodrow, N. C. O. Tomkinson, Synlett, 2009,
798-802.