Hexacarbonylmolybdenum-induced Reaction of Isoxazoles. Cycloaddition of Isoxazoles with Acetylenic Esters and Related Reactions
作者:Tomoshige Kobayashi、Makoto Nitta
DOI:10.1246/bcsj.58.152
日期:1985.1
undergo a cycloaddition reaction with dimethyl acetylenedicarboxylate across the C-4–C-5 bond to give 3,4-bis(methoxycarbonyl)pyridine derivatives. In a similar cycloadition of isoxazoles with methyl propiolate, 4-(methoxycarbonyl)pyridine derivatives were also obtained. The β-carbon atom of methyl propiolate could intervene in the bonding with the C-5 position of the isoxazoles regioselectively. A mechanism
在六羰基钼的存在下,取代的异恶唑与乙炔二羧酸二甲酯通过 C-4-C-5 键发生环加成反应,得到 3,4-双(甲氧基羰基)吡啶衍生物。在异恶唑与丙炔酸甲酯的类似环加成反应中,还获得了 4-(甲氧基羰基)吡啶衍生物。丙炔酸甲酯的β-碳原子可以区域选择性地干预与异恶唑C-5位的键合。涉及复合的 2-oxa-3-azabicyclo[3.2.0]hepta-3,6-diene 衍生物和随后的 N-O 和 C-1-C-5 键断裂导致复合(β-酮乙烯基) 硝基中间体被提议用于形成吡啶衍生物。为了阐明机理方面,4-苯基-2-氧杂-3-氮杂双环[3.2.0]庚-3的反应,