The statistical method of least squares has been applied to the estimation of energy and entropy of activation when there is available a variable number of experimental values of the kinetic constant, at several temperatures.Furthermore, the method is described, by which the variances of the estimates can be calculated, and significance tests applied to them.
s.a., 95 rue Gatti de Gamond, Enamine acylation with phosgene yields a chlorocarbonyliminium salt or an enamino-acyl chloride depending on whether the enamine does or does not bear a P-hydrogen atom. The reaction. which occurs under milder conditions than methoxycarbonylation with methyl chloroformate, provides reactive intermediates for the synthesis of p-keto-acid derivatives and heterocyclic compounds. In particular, enamino-esters have been obtained by methanolysis of enamino-acyl chlorides and used in the preparation of several new polycyclic pyrimidones derived structurally from pyrido[l,2-a] pyrimidin-4-one. The configurations of two enamino-esters and their corresponding amides are discussed. Brussels 18, Belgium ACYLATION of enamines with various acyl chlorides has been used in the synthesis of 2-acyl ketones and related compounds.l Reaction with phosgene, on the other hand, has received only limited attention. 1,2,3-Trimethyl-2-methyleneindoline has been reported to react with phosgene to give a symmetrical ketone,2 and the preparation of a-formyl amides by reaction of phosgene with enamines derived from a-disubstituted aldehydes and subsequent basic hydrolysis has been de~cribed.~ These isolated instances show that phosgene is a potentially powerful acylating agent for enamines; the reaction should afford a cheap and convenient method of preparing (3-keto-acid derivatives from aldehydes and ketones.$ We have studied the reaction with phosgene of a set of enamines derived from ct-substituted and
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