A Facile Cleavage of Ketone N,N-Dimethylhydrazones by CeCl3 · 7 H2O-SiO2

Abstract

Ketone N,N-dimethylhydrazones are rapidly and chemoselectively deprotected to the corresponding ketones in high yields by CeCl 3 •7H 2 O supported on silica gel under microwave irradiation. The method is compatible with acid sensitive substrates.

Protection and deprotection chemistry catalyzed by zirconium oxychloride octahydrate (ZrOCl2·8H2O)

“…When two equivalents of hydrazine hydrate were used for masking both the carbonyl moieties, we did not observe any reaction occurring at both the carbonyl groups, that is selectively only mono-hydrazones were obtained. We believe that the active species, zirconium cation cluster [Zr 4 (OH) 8 (H 2 O) 16 ] 8 ' is too bulky to coordinate with the two carbonyl groups at the same time. Hence, complexation with only one carbonyl group is possible and thus showing the chemoselectivity.…”

CeCl3 · 7H2O/SiO2 as an Efficient and Recyclable Catalyst for the Synthesis of Dihydropyrano[3,2‐b]chromenediones

“…e development of promoted organic reactions using air-stable and water-tolerant lanthanide salts as Lewis acid catalyst is one of the important and challenging subjects in synthesis organic chemistry. In the past few years, Cerium(III) chloride heptahydrate adsorbed on silica gel (CeCl 3 ⋅7H 2 O/SiO 2 ) has emerged as a potential catalyst in affecting various organic transformations due to its high catalytic ability, water tolerance, economic viability, and reusability [12,13]. Herein we report an efficient, green, and simple method for the synthesis of dihydropyrano [3,2b]chromenediones via the condensation of aromatic aldehydes, kojic acid, and dimedone, in the presence of catalytic amount of CeCl 3 ⋅7H 2 O/SiO 2 at 110 ∘ C under solvent-free conditions (Scheme 1).…”

Poly(N-bromoacrylamide): an efficient and useful catalyst for the protection of carbonyl compounds as dithiolanes, dithianes and oxathiolanes under solvent-free and microwave conditions

“…Recently, methods employing catalysts such as N-bromosuccinimide [4,5], *Corresponding author. E-mail: tamami@chem.susc.ac.ir tricholoro isocyanoric acid [6], I 2 [7], AlCl 3 -SiO 2 [8], NaHSO 4 -SiO 2 [9], PPA-SiO 2 [10], silica chloride [11], p-TsOH-silica gel [12], montimorillonite K-10 [13], H 3 PW 12 O 40 /SiO 2 [14], LiBF 4 [15], MoO 2 (acac) 2 [16], SnCl 2 .2H 2 O [17], Bi(NO 3 ) 3 [18], ScCl 3 [19], NiCl 2 [20], InCl 3 [21,] ZrCl 4 [22], WCl 6 [23], LiBr [24], Y(OTf) 3 [25], VO(OTf) 2 [26], Sc(OTf) 3 [27,28] have also been reported in the literature. However, many of these procedures are associated with certain limitations such as low yields, harsh reaction conditions, difficulties in work-up, requirement for an inert atmosphere, use of stoichiometric reagents, sensitivity to moisture, long reaction times, cost, and inconvenience in handling the reagents or catalysts.…”