Dehydroaporphines from aporphines

Dehydroaporphines have been prepared from aporphines by photo-oxidation (Castedo et al.. Heterocycles, 1981, 915 ... 

Recently, a photosensitized synthesis of phenanthrene heterocycles from 1- and 9-(aminoalkyl)phenanthrenes has been achieved109. Irradiation of l-(2-aminoethyl)phen-anthrene and m-DCNB in 9 1 acetonitrile water solution for 2 hours gives 70% of the aporphine 114 and 15% of the dehydroaporphine 115 with 87% conversion of starting material (equation 50). 

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... 

More recently, the preparative value of VOCl3 and VOF3-TFA in chemical oxidation has been demonstrated (see Section III, on the pro-aporphine and promorphinane alkaloids) (415,462). Some other authors used the purified enzyme horseradish peroxidase (463). By this method the aporphine base (besides the quaternary dibenzopyrrocoline) is readily obtained from (S)-( + )-laudanosoline hydrobromide or from (/ )-(—)-laudanosoline methiodide with retention of the absolute configuration. The synthesis of 6a,7-dehydroaporphine bases was also carried out by making use of the benzyne reaction (439). Reduction of these substances affords the corresponding aporphine bases (439). The synthesis of isoquinoline alkaloids by lead tetraacetate oxidation was reviewed by Umezawa and Hoshino (343). 

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