RESUMO
The Castagnoli-Cushman reaction of 3,4-dihydroisoquinolines with glutaric anhydride, its oxygen and sulfur analogues was investigated as a one-step approach to the benzo[a]quinolizidine system and its heterocyclic analogs. An extension towards the pyrrolo[2,1-a]isoquinoline system was achieved with the use of succinic anhydride. The results are evidence of an unexplored method for the access of the aforementioned tricyclic annelated systems incorporating a bridgehead nitrogen atom. The structures and relative configurations of the new compounds were established by means of 1D and 2D NMR techniques. The reactions between 1-methyldihydroisoquinoline and glutaric, diglycolic and succinic anhydrides yielded unexpected isoquinoline derivatives containing an exocyclic double bond. The compounds prepared bear the potential to become building blocks for future synthetic bioactive molecules.
RESUMO
The 2,9,10-trioxatricyclo[4.3.1.0(3,8)]decane moiety is a tetracyclic cage-like orthoester incorporated in the structure of a series of daphnane derivatives such as resiniferatoxin (RTX), kirkinine, synaptolepis factors, huratoxin etc., exhibiting various biological activities. The approaches to the preparation of cage-like orthoesters starting from partially acylated or unmodified 1,2,4-trihydroxycyclohexane moieties built onto natural as well as synthetic compounds are discussed. Orthoester derivatives of RTX analogs, Ceverathrum alkaloids, myoinositol and pyranoses are included. Stereochemical requirements to the formation of the orthoester unit are discussed. The biological activity of different compounds containing the cage-like orthoester structural fragment is given. The literature is reviewed till 2004.
