Despite many published syntheses of chromones, none has been reported to be both selective for chromones and tolerant of ring substitution. The addition of substituted phenols to dimethyl acetylenedicarboxylate is now reported as a versatile high yield initial step in a simple three-step synthesis of chromone 2-carboxylic acids. Triethylamine being used to deprotonate the substituted phenol, the addition to dimethyl acetylenedicarboxylate proceeds under mild conditions and tolerates a wide range of functional groups on the phenol. Although not stereoselective, both fumarate and maleate aryloxy products of this addition can then be cyclized, according to a known method, to chromones without contamination by isomeric coumarins. Thus the addition reaction is a valuable component of a versatile and selective synthesis of substituted chromones.
尽管已发表了许多色酮的合成方法,但还没有任何一种方法既对色酮具有选择性,又对环的取代具有耐受性。现在有报道称,将取代苯酚加到乙炔二甲酸二甲酯上是一种多功能的高产率初始步骤,可简单地三步合成铬酮 2-羧酸。使用三乙胺对取代的苯酚进行去质子化,与乙炔二甲酸二甲酯的加成反应在温和的条件下进行,并可容忍苯酚上的多种官能团。虽然不具有立体选择性,但根据已知的方法,这种加成反应的富马酸酯和马来酸酯芳氧基产物都可以环化成色酮,而不会受到异构香豆素的污染。因此,该加成反应是取代色酮的多功能选择性合成的重要组成部分。