A method of making a compound of Formula I:
is carried out by condensing a pair of compounds of Formula II (which pair may be the same or different), or by condensing a compound of Formula III with a compound Formula IV,
to produce a compound of Formula I. The condensing step may be carried out with a metal salt under basic conditions.
将公式I的化合物制备方法是通过将两种公式II的化合物(这两种化合物可以相同也可以不同)或者将公式III的化合物与公式IV的化合物进行缩合,从而产生公式I的化合物。缩合步骤可以在碱性条件下使用
金属盐进行。