During the preparation of these bivalent candidates, the key step is the demethylation of (+)-meptazinol to give (+)-N-demethyl-meptazinol.Several methods were employed to demethylate meptazinol.

• 将双配基设计的方法用于美普他酚，以镇痛活性更优的(+)-美普他酚为母体，设计并合成了六个不同长度烃链连接的(+)-去甲美普他酚双配基。