76-67-5Relevant articles and documents
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Wallingford,Jones
, p. 578 ()
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The use of dialkyl carbonates for safe and highly selective alkylations of methylene-active compounds. A process without waste production
Bomben, Andrea,Selva, Maurizio,Tundo, Pietro
, p. 256 - 260 (2007/10/03)
The non-toxic compound dimethyl carbonate (DMC) can be used as a methylating and a methoxycarbonylating agent in place of methyl chloride and phosgene, respectively. We report here that DMC and other dialkyl carbonates (DAlkCs: dimethyl, diethyl and dibenzyl carbonates) allow very selective alkylations of a variety of CH2-acidic compounds. Both arylacetonitriles and alkyl arylacetates react with DAIkCs to yield the mono-C-alkylated derivatives (α-alkyl-α-arylacetonitriles and alkyl α-alkyl-α-arylacetates) with a selectivity of up to 99%, at complete conversion. Likewise, the mono-C-methylation by DMC proceeds selectively also on (aryloxy)acetonitriles and methyl (aryloxy)acetates. The reactions are carried out at temperature of 180-220°C in the presence of weak bases (usually K2CO3); under such conditions, DAlkCs efficiently replace the common and very toxic alkylating agents (dialkyl sulfates and alkyl halides). In addition to the high selectivity obtained and the intrinsic safety of the dialkyl carbonates, the reported reactions give rise to neither organic nor inorganic waste products.
THE ADDITION REACTION OF DIALKYL CARBONATES TO KETONES
Selva, Maurizio,Marques, Carlos Alberto,Tundo, Pietro
, p. 515 - 518 (2007/10/02)
The reaction of benzyl phenyl ketone with dimethyl carbonate gives methyl benzoate and methyl phenylacetate; diethyl carbonate gives the corresponding ethyl esters.The reaction takes place at high temperature (about 200 deg C) and in the presence of potassium carbonate as a catalyst.Other benzyl ketones react similarly.Aliphatic ketones yield a less selective addition.Accordingly, cyclohexanone with dimethyl carbonate gives dimethyl pimelate.The reaction is a retro-Claisen condensation, which occurs through the intermediate formation of the alkoxycarbonyl derivative.
Arylation of Diethyl Alkylmalonates: Synthetic Route to Diethyl Alkyl(substituted Aryl)malonates with the Aid of Temporary Arene Complexation by the Cyclopentadienyliron Moiety
Piorko, Adam,Abd-El-Aziz, Alaa S.,Lee, Choi Chuck,Sutherland, Ronald G.
, p. 469 - 475 (2007/10/02)
Nucleophilic substitution of chlorine in the ironcyclopentadienyl hexafluorophosphates of chlorobenzene, isomeric chlorotoluenes and dichlorobenzenes (1) with the anions generated from diethyl alkylmalonates (2) and (3) leads to the formation of ironcyclopentadienyl complexes of diethyl alkyl(substituted phenyl)malonates (4) and (5).An excess of the anion employed in reactions with the m- and p-dichlorobenzene complexes leads to substitution of both chlorine atoms and formation of isomeric phenylenedimalonate complexes (8).Malonyl cations (4) and (5) possessing a chloro substituent on the complexed phenyl ring provide the possibility of further modifications of phenyl ring substituents via substitution or addition reactions .The described complexes have been demetallated giving diethyl alkyl(substituted phenyl)malonates in >50percent overall yield from the cations (1).All the complexes and compounds have been fully characterized.This approach to the synthesis of the diethyl alkyl(substituted phenyl)malonates which are intermediates in the synthesis of important biologically active barbiturates is easy, efficient, and currently the most general in the area.
