Rhoeadane alkaloids

The dimeric alkaloid stepionine was isolated from Stephania japonica Miers. (Formosa) (723). Reductive fission transforms it into the 3-benz-azepine derivative, which is closely related to the rhoeadane alkaloids. It has also been prepared synthetically (724). 

The second method consisted of the conversion of natural phthali-detetrahydroisoquinolines (123) into rhoeadane alkaloids (732, 733) (Scheme 56). 

Scheme 53. The total synthesis of rhoeadane alkaloids (154) via photosensitized oxidation of an enaminoketone (729).

Scheme 59. Degradation of rhoeadane alkaloids (153) for the study of their biogenesis (744).

CD Data of the f. Santavy TABLE VI Rhoeadane Alkaloids at Room Temperature (752)... 

Slavik showed that the presence of the rhoeadane alkaloids is not restricted to the plants of the genus Papaver but also to those of Bocconia and Meconopsis (33, 50,221). Dimeric alkaloids were found in the plants of the genus Bocconia, Dicentra, Papaver, and Sanguinaria (see Table I). 

Pharmacological Activity Other Biological Activity Protoberberidine Alkaloids Biosynthesis Biological Activity Protopine Alkaloids Benzophenanthridine Alkaloids Phthalideisoquinoline Alkaloids Rhoeadane Alkaloids Dibenzopyrrocoline Alkaloids Pavine and Isopavine (Argemone) Alkaloids Cularine Alkaloids Bisbenzylisoquinoline Alkaloids Biological Activity... 

Synthetic work on rhoeadan and other benzazepine alkaloids has been reviewed. The synthesis of benzindenoazepines from l-benzoyl-3,4-dihydroisoquinolines cf. Vol. 6, p. 158) has been applied to the preparation of methylenedioxy analogues, e.g. (162). An alternative to the published procedure... 

Narcotine can be split into cotarnine and opianic acid by treatment with dilute sulfuric acid by oxidation with dilute nitric acid, chromic acid, potassium permanganate or with mercuric acetate (691). Hydrogenolysis (hydrochloric acid or sulfuric acid and zinc) affords hydrocotarnine and meconine. Treatment of hydrocotarnine with sodium in ethanol leads to cleavage of the methoxyl group with the formation of 8-hydroxy-1,2-dihydrohydrastinine. The phthalidetetrahydroisoquinoline alkaloids can be converted into rhoeadane see Section III,M and spirobenzylisoquinoline (see Section 111,0,1) precursors (692). 

The alkaloids of the narcotine type can also be synthesized from benz[d]indeno(l,2-f ]azepine (133a) (698) (Scheme 45). Moreover, compound 133a forms a key substance for the synthesis of the tetrahydro-protoberberine (58), protopine (101), rhoeadane (154), and spiroben-zylisoquinoline (191) ring skeletons. The compounds 133a and 133b arise also by rearrangement from the spirobenzylisoquinoline, protoberberine, and 1-benzoylisoquinoline skeletons. Therefore, it is assumed that even in the plants it plays a key role in the formation and interconversion of the benzylisoquinoline alkaloids with 17 carbon atoms in the skeleton (Scheme 45). 

Scheme 54. A suggested pathway for the in vivo transformation of tetrahydroprotoberberine metho salts via 13-oxoprotoberberinium salts (160) into alkaloids of narceine (144) and rhoeadane types (152) (730). , —signifies 14Clabels.

Scheme 56. Conversion of phthalidetetrahydroisoquinoline alkaloids (123) into alkaloids of rhoeadane type (154) (733).

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