Decarboxylation acylmalonate

The major advantages of this procedure over the enol sulfonate procedure lie in the availability of diethyl 2-chloro-2-cyclopropylethene-l,l-dicarboxylate from the corresponding acylmalonate and phosphorus oxychloride, and the fast, homogeneous, decarboxyl ative elimination reaction of the triethylamine salt of the half-ester in dry organic solvents. The conditions described here, with slight modifications (overnight treatment), have been used for a variety of g-chloro alkyl idene/aryl idene malonates as shown in Table I. 

Olefin elimination and decarboxylation of ethyl t-butyl acylmalonates proceeds easily on treatment with toluenesulfonic acid to form /3-keto esters of the type RCOCH,CO,C,Hj. By this procedure, acyl acetates where R is ethyl (63%), cyclohexyl (65%), 2-furyl (70%), benzyl (46%), or propenyl (35%) have been prepared. The limiting factor in this excellent method is the availability of ethyl t-butyl malonate its synthesis has been described. ... 

The reagent is used in a general method for the conversion of an acid chloride into an acylmalonic ester which on hydrogenolysis and decarboxylation yields a methyl ketone. the procedure formulated is that used at one stage in the total synthesis of aldosterone. ... 

Hydrolysis and decarboxylation of acylmalonic esters, which also react as / -oxo acids, affords methyl ketones ... 

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