A New, Mild, General and Efficient Route to Aryl Ethyl Carbonates in Solvent‐Free Conditions Promoted by Magnesium Perchlorate

Abstract

A new, general and mild method for the direct synthesis of aryl and alkyl ethyl carbonates promoted by a Lewis acid is reported. The reaction proceeds smoothly with diethyl dicarbonate in the presence of Mg(ClO 4 ) 2 , a specific activator of 1,3-dicarbonyl compounds, and shows general applicability.

Recent Development about the Use of Pyrocarbonates as Activator in Organic Synthesis: A Review

“…In fact, as we demonstrated, triflate and perchlorate salts mainly decompose Boc 2 O, whereas weak Lewis acids can exploit the reaction [33]. On the other hand more stable pyrocarbonates are less influenced by the Lewis acid strength, as already demonstrated in this review [33,35]. The best choice was anhydrous as well as hydrated magnesium chloride; since both reagents give clean reactions and they also have very low costs and toxicity so their waste does not cause environmental problems.…”

“…In the previous section, the opportunity to address the reaction of alcohols with Boc 2 O towards aryl and alkyl tert-butyl ethers or the corresponding Boc derivative formation, depending on the Lewis acid catalyst has been discussed (Scheme 7) [33]. The synthesis of ethers is peculiar to Boc 2 O, which has a characteristic decomposition, whereas other dicarbonates such as Eoc 2 O exclusively lead to Eoc-alcohols [35]. Therefore, an interaction between some electrophilic species arising from Boc 2 O selfdecomposition and alcohol appeared to be reasonably involved into the reaction mechanism.…”

“…However, an efficient and simple protocol for the direct synthesis of mixed aryl alkyl carbonates under acidic conditions has appeared in literature only recently [35]. The reaction is carried out under solvent-free conditions, since all the solid alcohols dissolved in Eoc 2 O at 40 °C.…”

Highly Selective Primary Alkoxycarboxylation and Esterification of Unprotected Pyranose Derivatives Mediated by Scandium(III) Triflate Catalysis

“…[5] Bartoli and co-workers have also reported the ethoxycarboxylation of phenols by using diethyl pyrocarbonate with Lewis acid catalysis. Similarly, the reactivity of dicarbonates and anhydrides with primary and secondary alcohols by using Lewis acid catalysis [6] has been reported. [ Selective esterification or alkoxycarboxylation of the 6Јhydroxy group of unprotected pyranose derivatives is a difficult synthetic challenge.…”

Taking Up the Cudgels for Perchlorates: Uses and Applications in Organic Reactions under Mild Conditions

“…[49] Moreover they can act as useful protecting groups for alcohols and phenols since they are more stable than the corresponding esters under basic conditions, Scheme 17. so a very efficient methodology for the synthesis of aryl and alkyl ethyl carbonates 35 and 36 has been established (Scheme 17). [50] The method works at low temperature and under SFCs.…”