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Reactions >> Protecting Groups >> Stability

Acetonides

T. W. Green, P. G. M. Wuts,
Protective Groups in Organic Synthesis,
Wiley-Interscience, New York, 1999, 207-215, 716-719.

 

Stability

H2O: pH < 1, 100C pH = 1, RT pH = 4, RT pH = 9, RT pH = 12, RT pH > 12, 100C
Bases: LDA NEt3, Py t-BuOK Others: DCC SOCl2
Nucleophiles: RLi RMgX RCuLi Enolates NH3, RNH2 NaOCH3
Electrophiles: RCOCl RCHO CH3I Others: :CCl2 Bu3SnH
Reduction: H2 / Ni H2 / Rh Zn / HCl Na / NH3 LiAlH4 NaBH4
Oxidation: KMnO4 OsO4 CrO3 / Py RCOOOH I2, Br2, Cl2 MnO2 / CH2Cl2

Protection


ZrCl4 was an efficient catalyst for  the deprotection of 1,3-dioxalanes, bis-TBDMS ethers, and diacetate functional groups in excellent yields. ZrCl4 also promoted diol protection as the acetonide in very good yields  and acted as a transesterification catalyst for a range of esters.
S. Singh, C. D. Duffy, S. T. A. Shah, P. J. Guiry, J. Org. Chem., 2008, 73, 6429-6432.


Molecular iodine catalyzes acetalation and acetylation of sugars with stoichiometric amounts of enol acetates under solvent-free conditions to give orthogonally protected sugar derivatives in short time and good yields. At lower temperature, it is possible to obtain the acetonide acetate as a single product whereas peracetate is the major product at higher temperature.
D. Mukherjee, B. A. Shah, P. Gupta, S. C. Taneja, J. Org. Chem., 2007, 72, 8965-8969.

Other Syntheses of Acetonides


Transformation of epoxides to β-alkoxy alcohols, acetonides, and α-alkoxy ketones is achieved by using molybdenum(VI) dichloride dioxide (MoO2Cl2) as a catalyst. Alcohol, aldehyde, oxime, tosyl, and tert-butyldimethylsilyl functional groups are tolerated during the methanolysis and acetonidation of the functionalized epoxides.
K. Jeyakumar, D. K. Chand, Synthesis, 2008, 807-819.

Deprotection


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.


ZrCl4 was an efficient catalyst for  the deprotection of 1,3-dioxalanes, bis-TBDMS ethers, and diacetate functional groups in excellent yields. ZrCl4 also promoted diol protection as the acetonide in very good yields  and acted as a transesterification catalyst for a range of esters.
S. Singh, C. D. Duffy, S. T. A. Shah, P. J. Guiry, J. Org. Chem., 2008, 73, 6429-6432.


Aqueous tert-butyl hydroperoxide (70%) is an inexpensive reagent for the regioselective and chemoselective deprotection of terminal acetonide groups. Various acetonide derivatives furnish the corresponding deprotected diols in good yields, while a large number of acid labile protecting functional groups and other functional moieties were found to be unaffected under the conditions.
M. R. Maddani, K. R. Prabhu, Synlett, 2011, 821-825.


Asymmetric Synthesis of 1-(2- and 3-Haloalkyl)azetidin-2-ones as Precursors for Novel Piperazine, Morpholine, and 1,4-Diazepane Annulated Beta-Lactams
W. Van Brabandt, M. Vanwalleghem, M. D'hooghe, N. De Kimpe, J. Org. Chem., 2006, 71, 7083-7086.


Indium trichloride in an acetonitrile-water mixture chemoselectively cleaved the isopropylidene acetals of various 1,3-dioxolanyl-substituted 1,2-oxazines as well as carbohydrate derivatives. Enol ethers, glycosidic linkages and acid-sensitive protecting groups such as tert-butyldimethylsilyl, 2-(trimethylsilyl)ethyl, or tert-butoxycarbonyl are not attacked.
F. Pfrengle, V. Dekaris, L. Schefzig, R. Zimmer, H.-U. Reissig, Synlett, 2008, 2965-2968.