Summary.
3,4-Dihydroisoquinoline-Reissert-compounds were alkylated to 1-benzyl- and 1-picolyl-derivatives, which in turn could selectively be hydrolized yielding various carboxylic acids, among others certain amino acids related to 3′,4′-deoxynorlaudanosoline carboxylic acid (DNLCA). These on treating with ethanolic KOH underwent cyclization to dibenzoquinolizine- and isoquinonaphthyridine-13a-carboxylic acids. Alternatively this cyclization also could be achieved by a more convenient one-pot procedure starting from the same dihydro-Reissert-compounds. Thermal decarboxylation afforded among others the alangia alkaloids alangimarine and dihydroalangimarine.
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Part of PhD thesis, LMU München, D
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Reimann, E., Grasberger, F. Protoberberines from Reissert-Compounds. Part IX [1]. An Alternative Approach to Dibenzoquinolizine- and Isoquinonaphthyridin-13a-carboxylic Acids, a Novel Synthesis of Alangimarine. Monatshefte für Chemie 136, 193–209 (2005). https://doi.org/10.1007/s00706-004-0231-5
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DOI: https://doi.org/10.1007/s00706-004-0231-5