Cerium(IV) Ammonium Nitrate-catalyzed Synthesis of β-Keto Enol Ethers from Cyclic β-Diketones and Their Deprotection

Abstract

A mild and efficient method for etherification of cyclic -diketones with alcohols has been developed using a catalytic amount of cerium(IV) ammonium nitrate at room temperature to afford the corresponding -keto enol ethers in good to excellent yields. The deprotections of enol ethers in water-acetonitrile (1:1) using a catalytic amount (10 mol %) of cerium(IV) ammonium nitrate have also been achieved.

Synthesis of tetracyclic chromenones via platinum(ii) chloride catalysed cascade cyclization of enediyne–enones

“…The compound 2 was prepared according to the literature procedure. 12 General procedure for synthesis of compounds 1a-1o…”

Methods for Vinyl Ether Synthesis

“…These enols can also undergo acid-catalyzed alcohol substitution in the presence of cerium(IV) ammonium nitrate to generate enol ethers, as demonstrated by the Roy group (Scheme 54). 64 Scheme 54 CAN-catalyzed enol ether formation from a 1,3-dicarbonyl…”

A study of Heck cyclization reactions to form phenanthridine ring systems

“…In order to assess the utility of these conditions on a substrate biased towards the formation of a single double bond isomer, we chose to synthesize the gem dimethyl analogue of the phenanthridine ring system, 11. The sulfonamide protected cyclization precursor 12 was readily accessed (Scheme 2) through conversion of dimedone to the known enone 13; 18,19 reduction of 13 to the corresponding enol and conversion to allylic bromide 14; 20.21 coupling of bromide 14 with 2-bromobenzylamine; and finally sulfonamide protection of the amine (6 steps, 13 % overall yield). Heck cyclization of 12 employing the Herrmann-Beller catalyst resulted in quantitative conversion in 2 h to a colourless solid which was shown to be the desired …”