Remarkably efficient deprotection of cyclic acetals and ketals

Ceric Ammonium Nitrate/Pyridine: A Mild Reagent for the Selective Deprotection of Cyclic Acetals and Ketals in the Presence of Acid Labile Protecting Groups

“…As for CAN, in addition to the two conditions reported 8,11 it has been used on SiO 2 for the selective removal of trityl and silyl groups 27 and for the opening of cyclic ketals erroneously 19 believed to occur under alkaline and/or neutral conditions. [28][29][30] In conclusion, the peculiar reactivity of Ce(IV), when used in the reagent system CAN/pyridine at pH = 4.4, has been highlighted. Under these conditions, the Lewis acidity of cerium was found to play a prominent role in the selective deprotection of several acetonides in the presence of other commonly used hydroxyl protecting groups.…”

Synthesis of (+)- and (-)-dihydromenisdaurilide and (+)- and (-)-dihydroaquilegiolide

“…Treatment with montmorillonite K-10 under the same conditions previously used in our group for the hydrolysis of structurally similar ketals resulted in no deprotection. The use of p-toluenesulfonic acid in acetone or cerium ammonium nitrate in an acetonitrile/water mixture 17,18 did not yield the desired ketone 13 either.…”

Mild and chemoselective catalytic deprotection of ketals and acetals using cerium(IV) ammonium nitrate

“…Over the past few years, milder protocols have emerged based upon the use of catalytic amounts of Lewis acids or of non acidic reagents. 4 In this context, we have recently described two original procedures for the unveiling of ketals and acetals using stoichiometric 5 and catalytic 6 amount of cerium(IV) ammonium nitrate (CAN). In this Article, we wish to describe our results in full and discuss in some details the intimate mechanism of this reaction (Fig.…”