Apparicine, isolation

Predictably, vobparicine originates from attack of the strongly nucleophilic C-22 of 66 on C-3 of 314. In fact, when a mixture of vobasinol and excess apparicine was refluxed for 2 hr in 1.5% methanolic HC1 under nitrogen, vobparicine was formed, identical in all respects with the natural product. Vobparicine was considered to be a genuine alkaloid because the conditions for its synthesis were not achieved during isolation procedure. 

The related alkaloids ervaticine (15) and apparicine (16a) have been isolated from the leaves of Ervatamia coronaria (85H(23)2975) and from the wood of Vallesia antillana (77MI249), respectively. The latter exhibits high antibacterial activity. Subsequently, 16(S)-hydroxy-16,22-dihydroapparicine (16b) was isolated from the leaves of T. dichotoma (84JNP835). 

Among compounds related to uleine that have been isolated from A. dasycarpon are X-noruleine (CCLVII-B), dasycarpidone (CCLVII-A), the corresponding alcohol, dasycarpidol, X-nordasycarpidone, and 1,1 -dihydro-l -hydroxyuleine. Dasycarpidone may be obtained from uleine by ozonolysis, or from dasycarpidol by oxidation with chromium trioxide in pyridine. l,l -Dihydro-l -hydroxyuleine has been synthesized from uleine by hydroboration (143b). Apparicine, an alkaloid of novel skeleton present in A. dasycarpon and several other species, has been shown to have the structure CCLVII-U (37). 

All the alkaloids belonging to this group in Sri Lankan plants have been isolated by Perera, Sandberg, Verpoorte, and co-workers from various parts of Tabernaemontana dichotoma of the family Apocynaceae. Apparicine... 

Strychnine-Akuammicine-Ellipticine Group. Akuammicine has been found in the seeds of Hunteria congolana and Na-methyl-2/3,16 -dihydroakuammicine in the leaves of Vinca minor. Tubotaiwine and condylocarpine occur in Aspid-osperma album tubotaiwine and apparicine have been isolated from Catharanthus ovalis, tubotaiwine also from Pandaca boiteau and Melodinus aeneus Baill., in the last of which tubotaiwine Nb-oxide also occurs. ... 

---