4.5- Dioxoaporphines

Aristolochla tuberosa has yielded two new 4,5-dioxoaporphines, tuberosinone (59) and tuberosinone N-6-D-glucoside (60). Condensation of benzyne with the masked diene (61) generated norcepharadione-B (62) in 407. yield apor-phines can also be prepared by a related approach (see Section 2 above). 

As mentioned previously, the dried fruits of Nandina domestica contain the new alkaloid 4,5-dioxodehydronantenine (55).34 

The new alkaloid 4,5-dioxodehydrocrebanine (71) has been obtained from Stephania sasakii11 and cepharadione A has been re-isolated from that same plant.4 

A total synthesis of pontevedrine (40) has been achieved, and is outlined in 

Reagents i, Bf2, HOAc ii, NH4OH, HOAc iii, hv, Oj, NaOH, MeOH iv, NaH, DMF, methyl fluorosulphonate 

Alternatively, pontevedrine has been prepared by direct photo-oxidation of glaucine or of dehydroglaucine/  

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The phenolic derivatives of this series, such as aristolochic acid la and 4,5-dioxoaporphine, suffered considerable bathochromic shifts, and further shifts toward the longer wavelength region are observed on addition of alkali. For instance, the UV spectrum of 4,5-dioxoaporphine (49), 246 (4.70), 292 (4.14), 305 (4.26), 318 (4.28), 459 (4.23), shifts to 241 (4.71), 256 (4.67), 305 (4.21), 331 (4.25), 510 (4.30) in alkaline solution (64). This bathochromic shift was also found in aristolochic acid la (50) (63, 65). The UV spectroscopic method has been used for the quantitative analysis of aristolochic acids from plants or pharmaceutical products (66-68,71). 

The partial synthesis of 4,5-dioxoaporphine has been achieved. Preparation of cepharadione B (43), 2,10-dimethoxy-4,5-dioxodehydroaporphine (84d), 4,5-dioxodehydronantenine (86d), and 4,5-dioxodehydrocrebanine (87d) was achieved in DMSO by air oxidation of the corresponding dehydroaporphines with an alkali catalyst as described above (Section V,A,1). Oxidation of nan-... 

A one-pot eonversion of 132 to norpontevedrine (135) was also carried out by irradiation of 132 in ethanolic alkali solution under an oxygen atmosphere in 33% yield. It may be stated that this method of synthesis of 4,5-dioxoaporphine seems to be of wide scope and therefore that different alkaloids of this type may be synthesized in a similar manner (96). 

C. Aporphine, oxa-aporphine, and proaporphine alkaloids (including dioxoaporphine, aristolactams, and phenanthrene alkaloids)... 

A useful and timely supplementary listing of new aporphines, oxoaporphines, phenanthrenes, and 4,5-dioxoaporphines has appeared.1 The alkaloids of Glaucium species, which include several aporphines and oxoaporphines, have been tabulated2 and a general discussion of the chemistry and biogenesis of isoquinoline alkaloids, including the aporphines, has been presented.3... 

Aerial oxidation of the dehydroaporphines (52)—(54) with alkali catalysts gives the corresponding oxoaporphines, 4,5-dioxoaporphines, and JV-methyl -aristolactams in low yields. The 4,5-dioxoaporphine (55) from the oxidation of (54) corresponds to 4,5-dioxodehydronantenine, which is found as a natural product in the dried fruits of Nandina domestica.34... 

Ouregidione (108) is a new 4,5-dioxoaporphine isolated from G. ouregou, where it is found together with the previously described norcepharadione B (107)... 

The 4,5-dioxoaporphine cepharadione-A (59) has now been claimed to be present in Piper sanctum (Piperaceae).70... 

Oxidation of noraporphines and aporphines with Fremy s salt gives oxoaporphines and oxoaporphinium salts, respectively.75 Aerial oxidation of dehydro-aporphines in the presence of alkali provides the corresponding oxoaporphines, 4,5-dioxoaporphines, and A-methylaristolactams.76 An analysis of the 13C n.m.r. 

Cepharadione-A and -B have also been found in Piper auritum, an example of the rare occurrence of isoquinoline alkaloids in the family Piperaceae. A new dioxoaporphine is norcepharadione-B (46), isolated from the callus tissue of Stephania cepharantha. ... 

Naturally occurring aristolactams, aristolochic acids and dioxoaporphines, having a phenanthrene chromophore, are a small group of compounds... 

The Tetitoxicum genus is closely related to some Abuta species such as A. imene and A. rufescens based on the constituents present which are mainly oxoaporphines and azafluoranthenes. It is possible dial 4,5-dioxoaporphines may also be present in some of these Abuta species. 

Several new aporphine and berberine alkaloids which were uncovered in the period of the last ten years or so are from plants of the Anixmaceae such as the 7-hydroxyaporphine, dasymachaline (9) from Desmosdasymachatus [27], the dioxoaporphine, l,2,3-trimethoxy-4,5-dioxo-6a,7-dehydroaporphine (10) from Pseuduvaria macrophylla [28], the tetrasubstituted... 

Desai, S.J., Chaturvedi, R.N., Badheka, L.P. and Mulchandani, N.B. (1989) Aristolactams and 4,5-dioxoaporphines from Indian Piper species. Indian Journal of Chemistry, Section B, 28B, 775—777. 

Dioxoaporphines constitute a relatively small group of aporphine alkaloids. Three 4,5-dioxoaporphines, namely, artabotrine (50), 8-methoxy-ouregidione (51), and ouregidione (52), have been isolated from the stem bark of Artabotrys zeylanicus (Annonaceae) (48,49). The structure of... 

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