Protoberberine ausReissert-Verbindungen, 2. Mitt.: Eine neue Synthese von 8-Methyldibenzo[a,g]chinolizidinen
作者:Eberhard Reimann、Helmut Renz
DOI:10.1002/ardp.19933260502
日期:——
Reissert‐Verbindungen 16 werden mit dem Benzylbromid 14 zu den Dihydroisochinolinen 5 benzyliert. Durch alkalische Spaltung bilden sich daraus die 1‐Benzylisochinoline 6, die mit Säure spontan zu den desoxygenierten Coralynen 4 cyclisieren. 4a sowie das aus 4b erhaltene Chinoliziniumsalz 18 werden mit NaBH4 zu den 8‐Methyl‐trans‐dibenzochinolizidinen 19 reduziert. Die Sequenz 5 → 6 → 4 → 19 beinhaltet einen
Protoberberine ausReissert-Verbindungen, 5. Mitt.: Synthese des (�)-Bharatamins
作者:E. Reimann、H. Renz、W. Dammertz、T. Scholz
DOI:10.1007/bf00807398
日期:1996.2
Alkylation of the Reissert compound 1 by methyl 2-bromomethylbenzoate (2) followed by spontaneous intramolecular cyclization affords dibenzo[a, g]quinolizinone 4 which in turn can be reduced to benzyl ether 5 by LiAlH4/NaBH4. Debenzylation of 5 by ethanolic HCl furnishes the title compound 6 in improved total yield.
Protoberberine ausReissert-Verbindungen, 4. Mitt. Eine neue Synthese des (�)-Alamaridins und des (�)-epi-Alamaridins
作者:E. Reimann、H. Renz
DOI:10.1007/bf00811089
日期:1994.12
A novel synthesis of 8-methylisoquino[2,1-b] [2,7]naphthyridinium salts 7 is reported using the intramolecular cyclization of the 1-substituted isoquinolines 5 as the key step, which in turn are obtained by alkylation of the Reissert compounds 1. The salts 7 can be reduced by NaBH4 yielding the 8 alpha- and 8 beta-methylstereomers (+/-)-alamaridine and (+/-)-epi-alamaridine 9c and 11c, respectively.
Protoberberines from Reissert-Compounds VIII [1]. Oxazoloisoquinolines, New and Efficient Educts for the Synthesis of 8-Oxoprotoberberines
作者:Eberhard Reimann、Fritz Grasberger、Kurt Polborn
DOI:10.1007/s00706-003-0013-5
日期:2003.6
Certain benzylated oxazoloisoquinolinones readily available fromReissert compounds provided an efficient access to 8-oxoprotoberberines in three steps. A series of these new precursors as well as several oxoprotoberberines were prepared and the scope and limitation of this procedure were investigated.