Tetracyclic Alkaloids Matrine Group

In addition to matrine and its A-oxide, Sophoraflavescens Ait. contains methyl cytisine, anagyrine, baptifoline, and a newly described base, sophoranol (CXXXV), C15H24ON2 (mp 171° [a]i) +66°), which is a hydroxymatrine 103, 104). The configuration of matrine has been 

Sophoranol may be obtained by the hydroxylation, which proceeds with unusual ease, of the product from the dehydrogenation of matrine with mercuric acetate. The dehydrogenation gives two dehydromatrines (CXXXVII and CXXXVIII), the former of which on reduction regenerates matrine the latter gives a mixture of matrine and mostly allomatrine (CXXXVI) 106). The latter is the more stable isomer and is the enantiomer of leontine 107). 

The configurations and conformation of matrine and allomatrine have been confirmed by NMR-spectra (5). The axial protons on C-11 and C-17 in matrine, in contrast with those on allomatrine, are shifted to lower fields because of the effect of the tertiary nitrogen, a fact entirely explicable by structure CXXXIV. 

The separation of sophocarpine and matrine can be achieved by one of two methods 108). The action of alkali hydrolysis matrine whereas sophocarpine remains unaffected or the X-oxides may be prepared by reaction with hydrogen peroxide and then separated by crystallization. 

Octadehydromatrine (CXL) and allomatridine are available synthetically from an azajulolidine 109). Alkaline hydrolysis of the pyridone and decarboxylation yields an octadehydromatrine (CXL) which under forcing conditions of hydrogenation gives allomatridine. 

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The most common group of alkaloids possessing a quinolizidine nucleus is that of the lupine alkaloids which can simply be classified as bicyclic (lupinine/epilupinine type), tricyclic (cytisine type) or tetracyclic, (sparteine/lupanine or matrine type). Fig. (23). This grouping is made according to structure complexity and without considering biosynthesis, as the detailed biosynthetic pathways are still not completely understood. 

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