Epimeric Isopavine N-Oxides from Roemeria refracta

Roemeria refracta DC. (Papaveraceae) of Turkish origin yielded two novel epimeric N-oxides, (-)-(5R, 11S,14R)-reframidine N-oxide ( = (-)-(5R, 11S,14R)-11,12-dihydro-14-methyl-11,5-(iminomethano)-5H -cyclohepta[1, 2-f: 4, 5-f']bis[1,3]benzodioxole 14-oxide; 1) and (-)-(5R, 11S, 14S)-reframidine N-oxide ( = (-)-(5R, 11S, 14S)-11, 12-dihydro-14-methyl-11, 5-(iminomethano)-5H-cyclohepta[1, 2-f:4, 5-f']bis[1, 3]benzodioxole 14-oxide; 2). The isolated (-)-roelactamine ( = (-)-11, 12-dihydro-14-methyl-11, 5-(iminomethano)-5H-cyclohepta[1, 2-f:4, 5-f']bis[1, 3]benzodioxol-15-one, 4) is the first natural isopavinoid incorporating a lactam group. The epimeric (-)-15-(2-oxopropyl)reframidines ( = (-)-1-[11, 12-dihydro-14-methyl-11, 5-(iminomethano)-5H-cyclohepta[1, 2-f:4, 5-f']bis[1, 3]benzodioxol-15-y1]propan-2-ones; 5/6) and the epimeric (-)-ethyl (reframidin-15-yl)acetates ( = (-)-ethyl [11, 12-dihydro-14-methyl-11, 5-(iminomethano)-5H-cyclohepta[1, 2-f:4, 5-f']bis[1, 3]benzodioxol-15-y1]acetates; 7/8) are probably artifacts. (±)-Coclaurine (9), (±)-N-methylcoclaurine (10), (-)-roemeridine (11), and N-feruloyltyramine (12) are also isolated from R. refracta together with the previously reported bases. Specific 13C-NMR assignments are reported for the first time for the isopavines. Copyright © 1992 Verlag GmbH & Co. KGaA, Weinheim