oxalate in the presence of sodium hydride in THF gave ethyl 5-aroyl-4-oxo-4H-pyran-2-carboxylates, from which 4-oxo-6-aryl-4H-pyran-2-carboxylic acids (6-arylcomanic acids) were obtained in high yields via acid-catalyzed deformylative rearrangement. 5-Aroyl-4-oxo-4H-pyran-2-carboxylic acids (5-aroylcomanic acids) were prepared via а ring-opening/ring-closure sequence by the reaction of 5-aroyl-2-carbethoxy-4-pyrones
1-芳基-2-(二甲基
氨基亚甲基)
丁烷-1,3-二酮与
草酸二乙酯在氢化
钠存在下于THF中反应,得到5-芳酰基-4-氧代-4 H-
吡喃-2-
羧酸乙酯通过酸催化的甲酰基化重排以高收率获得了4-氧代-6-芳基-4 H-
吡喃-2-
羧酸(6-芳基
马来酸)。通过开环/闭环顺序,通过5-芳酰基-2-碳乙氧基-4-
吡喃酮的反应,制备5-芳基-4-氧代-4 H-
吡喃-2-
羧酸(5-芳酰基马
甲酸)用
哌啶随后进行碱性
水解和酸化。