290333-05-0Relevant articles and documents
Carbodiimide-mediated preparation of the tricyclic pyrido[3′,2′:4,5]pyrrolo[1,2-c]pyrimidine ring system and its application to the synthesis of the potent antitumoral marine alkaloid variolin B and analog
Molina, Pedro,Fresneda, Pilar M.,Delgado, Santiago
, p. 489 - 499 (2007/10/03)
A total synthesis of the marine alkaloid variolin B has been completed in 13 steps in an overall yield of 6.5% from 3-formyl-4-methoxypyridine. Our approach is based on the sequential formation of the 7-azaindole ring, the tricyclic pyrido[3′,2′:4,5]pyrrolo[1,2-c]pyrimidine ring system, and finally installation of the 2-aminopyrimidine ring at C5. The required 7-azaindole ring appropriately substituted is formed by a modified indole synthesis involving a nitrene insertion process (two steps). Formation of the annelated pyrimidine ring is achieved by two routes both involving a carbodiimide-mediated cyclization process, which allow incorporation of the amine functionality at C9 of the core tricyclic (six steps). Installation of the northeast 2-aminopyrimidine ring at C5 is performed using the Bredereck protocol (three steps). Ultimate, thermal decarboxylation with concomitant O-methyl deprotection and further N-benzyl deprotection by the action of triflic acid completed the synthesis of the target natural product variolin B.
Synthetic studies towards the 2-aminopyrimidine alkaloids variolins and meridianins from marine origin
Fresneda, Pilar M.,Molina, Pedro,Delgado, Santiago,Bleda, Juan A.
, p. 4777 - 4780 (2007/10/03)
A nine-step synthesis of 9-amino-4-methoxypyrido[3',2':4,5]pyrrolo[1,2- c]pyrimidine, a tricyclic ring system present in the marine alkaloids variolins is described. The natural marine products meridianins C-E have been synthesized for the first time starting from N-protected 3-acylindoles. (C) 2000 Elsevier Science Ltd.