Categories: C=O Bond Formation > Synthesis of aldehydes >
Synthesis of aldehydes by deprotection or hydrolysis
Protecting Groups
Cyclic Acetals
1,3-Dithianes, 1,3-Dithiolanes
Recent Literature
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.
Deprotection of acetals and ketals can be achieved by using a catalytic
amount of sodium tetrakis(3,5-trifluoromethylphenyl)borate (NaBArF4)
in water at 30 °C. For example, a quantitative conversion of
2-phenyl-1,3-dioxolane into benzaldehyde was accomplished within five minutes.
C.-C. Chang, B.-S. Liao, S.-T. Liu, Synlett, 2007, 283-287.
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.
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.
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.
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.
A simple, mild and efficient procedure cleaves a wide range of ketoximes and
aldoximes to the corresponding carbonyl compounds in an aqueous medium using
catalytic amounts of potassium bromide and ammonium heptamolybdate tetrahydrate
in combination with hydrogen peroxide.
N. C. Ganguly, S. K. Barik, Synthesis, 2008,
425-428.
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.
Aqueous dimethylamine is an efficient reagent for the conversion of various
benzal halides to their corresponding benzaldehydes. The method represents a
novel, economical approach to acquire pure, substituted benzaldehydes from
commercially available, or easily prepared starting materials.
D. Bankston, Synthesis, 2004,
283-289.
Geminal diacetates and dipivalates were prepared in high yields through a
mild and efficient reaction of aldehydes with acetic anhydride or pivalic
anhydride using zirconium (IV) chloride as a catalyst under solvent free
conditions. Regeneration of aldehydes from the acylals was achieved using the
same catalyst in methanol.
G. Smitha, Ch. S. Reddy, Tetrahedron, 2003, 59,
9571-9576.
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.
