Biomimetic formation of macrocyclic spermine alkaloids
Dihydroxyverbacine (10), a precursor for oxidative phenol coupling, was obtained via (±)-buchnerine (14), whose synthesis is described. The oxidizing system hemin (ferriprotoporphyrin IX chloride)/H2O2 promoted intramolecular coupling of 10 to give the alkaloids aphelandrine (1), orantine (2), and chaenorpine (7). The alkaloids were identified by on-line coupled HPLC and atmospheric-pressure chemical-ionization (APCI) mass spectrometry.
Metal-Templated Macrolactamization of Triamino and Tetramino Esters. Facile Synthesis of Macrocyclic Spermidine and Spermine Alkaloids, (S)-(+)-Dihydroperiphylline, (±)-Buchnerine, (±)-Verbacine, (±)-Verbaskine, and (±)-Verbascenine
The total synthesis of spermidine and spermine alkaloids. (S)-(+)-dihydroperiphylline (1), (±)-buchnerine (2), (±)-verbacine (3), (±)-verbaskine (4), and (±)-verbascenine (5), is described. The construction of macrocyclic lactams has been efficiently accomplished by the metal-templated cyclization of triamino esters and tetraamino esters. It was also found that the antimony(III) ethoxide is useful as an intermolecular amidation catalyst.
Antimony-templated macrolactamization of tetraamino esters. Facile synthesis of macrocyclic spermine alkaloids, (±)-buchnerine, (±)-verbacine, (±)-verbaskine, and (±)-verbascenine
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Ishihara,Kuroki,Hanaki,Ohara,Yamamoto
p. 1569 - 1570
(2007/10/03)
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