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 -cyclohepta1, 2-f: 4, 5-f′]bis1,3]benzodioxole 14-oxide; 1 ) and (?)-(5R, 11S, 14S)-reframidine N-oxide ( = (?)-(5R, 11S, 14S)-11, 12-dihydro-14-methyl-11, 5-(iminomethano)-5H-cyclohepta1, 2-f:4, 5-f′]bis1, 3]benzodioxole 14-oxide; 2 ). The isolated (?)-roelactamine ( = (?)-11, 12-dihydro-14-methyl-11, 5-(iminomethano)-5H-cyclohepta1, 2-f:4, 5-f′]bis1, 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-cyclohepta1, 2-f:4, 5-f′]bis1, 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-cyclohepta1, 2-f:4, 5-f′]bis1, 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.