Categories: O-H Bond Formation >
Cleavage of acetals
Acetals and ketals are readily deprotected under neutral conditions in the presence of acetone and indium(III) trifluoromethanesulfonate as catalyst at room temperature or mild microwave heating conditions to give the corresponding aldehydes and ketones in good to excellent yields.
B. T. Gregg, K. C. Golden, J. F. Quinn, J. Org. Chem., 2007, 72, 5890-5893.
Er(OTf)3 is an efficient Lewis acid catalyst in a mild deprotection of benzylidene derivatives.
A. Procopio, R. Dalpozzo, A. De Nino, L. Maiuolo, M. Nardi, G. Romeo, Org. Biomol. Chem., 2005, 3, 4129-4133.
A simple and efficient method has been developed for chemoselective deprotection of phenolic methoxymethyl (MOM) ethers at room temperature using silica-supported sodium hydrogen sulfate as a heterogeneous catalyst.
C. Ramesh, N. Ravindranath, B. Das, J. Org. Chem., 2003, 68, 7101-7103.
The use of CeCl3·7H2O enables a highly selective cleavage of MEM ethers in high yields in refluxing acetonitrile under mild and neutral reaction conditions. The reaction tolerates other hydroxyl protecting groups such as Bn, TBDPS, Ac, Me, Tr, PMB, benzylidene, THP, MOM, BOM, and NHAc.
G. Sabitha, R. Satheesh Babu, M. Rajkumar, S. Srividya, J. S. Yadav, Org. Lett., 2001, 3, 1149-1151.
Different types of unsymmetrically protected diols are available from the methylene acetal in a one-pot procedure. Monoprotected 1,2-diols with a silyl group at the less hindered hydroxy group as well as with a MOM group at the more hindered can be isolated in good yields. The reaction conditions are mild without affecting other functional groups.
H. Fujioka, K. Senami, O. Kubo, K. Yahata, Y. Minamitsuji, T. Maegawa, Org. Lett., 2009, 11, 5138-5141.