Various alpha-keto-1,3,4-oxadiazole derivatives were synthesized through a sequential intermolecular dehydrochlorination/intramolecular aza-Wittig reaction of carboxylic acids and imidoyl chloride intermediates, which were generated by isocyanide-Nef reaction of acyl chlorides and (N-isocyanimine) triphenylphosphorane (1) in CH2Cl2 at room temperature. (C) 2011 Elsevier Ltd. All rights reserved.
Direct Annulation of Hydrazides to 1,3,4-Oxadiazoles via Oxidative C(CO)–C(Methyl) Bond Cleavage of Methyl Ketones
strategy for the synthesis of 1,3,4-oxadiazoles was established through direct annulation of hydrazides with methylketones. It was found that the use of K2CO3 as a base achieves an unexpected and highly efficient C–C bondcleavage. This reaction is proposed to go through oxidativecleavage of Csp3–H bonds, followed by cyclization and deacylation.
通过将酰肼与甲基酮直接环合,建立了一种合成1,3,4-恶二唑的新策略。发现使用K 2 CO 3作为碱可以实现意想不到且高效的C–C键裂解。建议该反应通过C sp 3 -H键的氧化裂解,然后环化和脱酰基。