Epimeric Isopavine N‐Oxides from Roemeria refracta
Articles > Article · 1992
Authors: Belkis Gözler, Mustafa Ali Önür, Serap Bilir, Manfred Hesse
Helvetica Chimica Acta, International, 1992, vol 75, pp 260-268
Summary
Abstract 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.