Categories: C=O Bond Formation > Synthesis of ketones >
Synthesis of ketones by hydrolysis or deprotection
Name Reactions
Protecting Groups
Cyclic Acetals
1,3-Dithianes, 1,3-Dithiolanes
Recent Literature
Oximes of various aldehydes and ketones can be converted to the
corresponding carbonyl compounds at room temperature in excellent yields
with 2-iodylbenzoic acid in water in the presence of β-cyclodextrin.
N. S. Krishnaveni, K. Surendra, Y. V. D. Nageswar, K. R. Rao, Synthesis, 2003, 1968-1969.
N-bromosaccharin is an efficient reagent for the oxidative cleavage of
oximes to the corresponding aldehydes and ketones under microwave irradiation in
a domestic microwave oven. This procedure features short reaction times, high
chemoselectivity (no over-oxidation), easy work-up and high yields.
A. Khazaei, A. A. Manesh, Synthesis,
2004,
1739-1740.
An efficient and convenient procedure has been developed for the hydrolysis
of thioacetals/thioketals to the corresponding carbonyl compounds in
excellent yields with o-iodoxybenzoic acid (IBX) in presence of
β-cyclodextrin (β-CD) in water under neutral conditions at room temperature.
N. S. Krishnaveni, K. Surendra, Y. V. D. Nageswar, K. R. Rao, Synthesis, 2003, 2295-2297.
Perchloric acid adsorbed on silica gel is an extremely efficient, inexpensive,
and reusable catalyst for the protection of aldehydes and ketones and the
subsequent deprotection. Acetalization was mostly carried out under solvent-free
conditions with trialkyl orthoformates, but weakly electrophilic carbonyl
compounds and substrates that can coordinate with the catalyst, required the
corresponding alcohol as solvent.
R. Kumar, D. Kumar, A. K. Chakraborti, Synthesis, 2007, 299-303.
Er(OTf)3 is a very gentle Lewis acid catalyst in the
chemoselective cleavage of alkyl and cyclic acetals and ketals at room
temperature in wet nitromethane.
R. Dalpozzo, A. De Nino, L. Maiuolo, M. Nardi, A. Procopio, A. Tagarelli, Synthesis, 2004, 496-498.
I2 catalyzes the deprotection of oximes and imines to the
corresponding carbonyl compounds under neutral conditions in a water/surfactant
system at 25-40°C in high yields.
P. Gogoi, P. Hazarika, D. Konwar, J. Org. Chem., 2005, 70,
1934-1936.
Silylated cyanohydrins of iodo-substituted aryl, heteroaryl, or cycloalkenyl
ketones undergo an I/Mg-exchange using i-PrMgCl·LiCl. After
subsequent reactions with electrophiles, a facile deprotection
produces polyfunctional ketones in good overall yiels. An extension to
aromatic iodoaldehydes is described.
C.-Y. Liu, H. Ren, P. Knochel, Org. Lett.,
2006, 8, 617-629.
A number of new reactions of IBX with heteroatom-containing substrates were
discovered and their utility was demonstrated. IBX was used for the generation
of imines from secondary amines in notably high yields, for the oxidative
aromatization of nitrogen heterocycles and for the cleavage of dithianes.
K. C. Nicolaou, C. J. N. Mathison, T. Montagnon, Angew. Chem. Int. Ed., 2003,
42, 4077-4082.
