The thermal decomposition of keto-ylides resulting from the reaction of m - and p-acetoxy benzoyl chlorides with Ph3P=CH-COOMe leads, after saponification to m- and p-phenylpropiolic acid respectively. Ortho substitution by an acyl group generally changes the orientation of the reaction Thus o.-acetoxy-. benzoyloxy- or phenylacetoxy benzoyl chlorides respectively afford:andin satisfactory yields. Saponification
间苯和对乙酰氧基
苯甲酰氯与Ph3P = CH-COOMe的反应导致的酮基的热分解分别在皂化为间
苯丙酸和对
苯丙酸后导致。酰基的邻位取代通常会改变反应的方向。苯甲酰氧基-或苯乙酰氧基
苯甲酰氯分别提供:和令人满意的产率。第一种和第二种的皂化得到:这构成了一条新的,方便的途径,可制得3-酰基
4-羟基
香豆素和11-羟基12 H-苯并(b)
氧杂蒽12-。这些最后产物的形成涉及该酰氧基取代基的羰基,而不是如先前在这些系列中观察到的酰
氯的羰基。