
%0 Journal Article
%A Nelson, ER 
%A Price, JR 
%T Alkaloids of the Australian Rutaceae: <I>Pentaceras australis</I> Hook. F. III. Identification of 4-Methylthiocanthin-6-one
%J Australian Journal of Chemistry
%D 1952/12/01
%V 5
%N 4
%P 768-781
%K 
%R https://doi.org/10.1071/CH9520768
%U https://www.publish.csiro.au/paper/CH9520768 
%X The alkaloid C15H10OSN2 occurring in the bark of Pentaceras australis Hook. f. is shown to be 4-methylthiocanthin-6-one. The lactam ring is opened by alcoholic alkali giving 2-methylthio-2-(1'-&#946;-carbolyl)acrylic acid, followed by the elimination of methyl mercaptan and recyclization to 4-hydroxycanthin-6-one. Confirmation of the relation- ship of the alkaloid to canthinone is provided by (i) the ultraviolet absorption spectra, (ii) the formation of methyl mercaptan and 4,5-dihydrocanthine by treatment with zinc and hydrochloric acid, and (iii) the formation, by treatment with Raney nickel, of canthinone, 4,5-dihydrocanthinone, or the methyl or ethyl esters of &#946;-carbolylpropionic acid, depending on the conditions employed. The alkaloid has been synthesized from &#946;-carboline-1-carboxylic acid by conversion of the acid chloride with malonic ester, followed by cyclization, to 4-hydroxycanthinone, thence to 4-chlorocanthinone which with potassium methyl mercaptide yields 4-methylthiocanthinone. The low basicity of the alkaloid is discussed, particularly in relation to the basicity of 4-methoxy- canthinone. 
