Synthetic analogs ofPeganum alkaloids. I. Synthesis of methoxy- and hydroxy-substituted deoxyvasicinones and deoxypeganines
Abstract6-Methoxy-, 7-methoxy-, and ′8-methoxydeoxyvasicinones have been synthesized by the reaction of substituted (3-methoxy-, 4-methoxy-, and 5-methoxy-) anthranilic acids with α-pyrrolidone. The demethylation of these compounds has given the corre-sponding hydroxy-substituted analogs of deoxyvasicinone, and the reduction of the products obtained with zinc in hydrochloric acid has given the hydroxy- and methoxy- analogs of deoxypeganine. 8-Hydrooxydeoxypeganine dimethyl-, ethyl-, and butylcarbamates have been obtained by the carbamoylation of 8-hydroxydeoxypeganine.
Die Reaktion cyclischer Lactimäther mit Aminocarbonsäuren
Cyclische Lactimather reagieren mit aliphatischen und aromatischen, Aminocarbonsauren zunachst unter Bildung offenkettiger amidinartiger Verbindungen, die in der aliphatischen Reihe nur schwer zum Ring geschlossen werden konnen. Der Ringschlus vollzieht sich bei aromatischen und heterocyclischen o-Amino-carbonsauren sehr leicht. Die neue Synthese macht auch das Alkaloid Rutaecarpin (XV) leicht zuganglich.
New method for analysis of enzymatic reactions: Thermolysin-catalyzed synthesis of aspartame precursor
Aspartame is an artificial sweetener which is 200 times sweeter than sucrose. A precursor of aspartame, N-(benzyloxycarbonyl)-l-aspartyl-l-phenylalanine methyl ester (Z-APM) was synthesized and hydrolyzed with thermolysin in an aqueous monophasic system. Graphical plotting methods and/or nonlinear regression have been used to analyze enzymatic reactions because of the nonlinearity of enzymatic rate equations. There are, however, problems: the former require accurate measurement of the initial reaction rate and the latter gives no analytical information. The authors proposed a method to solve the nonlinear enzymatic rate equations with respect to the concentration of a product with the Taylor expansion, especially for the reversible Theorell-Chance mechanism (Murakami, Y., Hirata, M., and Hirata, A., J. Ferment. Bioeng., 82, 246–252, 1996). This solution, however, is complex for practical use. In this paper, a simpler solution to explain the thermolysin-catalyzed synthesis of Z-APM is obtained. New methods to determine the kinetic parameters, especially for the reversible Theorell-Chance mechanism, based on the approximated solution are proposed. The results calculated using the obtained kinetic parameters can satisfactorily explain the experimental results, which demonstrates the effectiveness of the proposed analysis. We must know the relation between the concentrations of substrates and a product, and accurately evaluate of the result obtained using Taylor expansion when we determine the kinetic parameters using our newly developed methods. The methods to determine the kinetic parameters of the reversible Theorell-Chance mechanism described in this paper is, however, expected to be applied to general enzymatic reactions.