Fischer Indolization of Ethyl Pyruvate 2-Bis(2-methoxyphenyl)hydrazone and New Insight into the Mechanism of Fischer Indolization. (Fischer Indolization and Its Related Compounds. XXVII)

摘要

In connection with studies on the direction of cyclization in the Fischer indolization of substituted di-phenylhydrazones, the Fischer indolization of ethyl pyruvate 2-bis(2-methoxyphenyl)hydrazone (6) was carried out. The result showed that cyclization in Fischer indolization of diphenylhydrazone does not always proceed to the electron-richer nucleus, but depends on the conformation of the enehydrazine. Thus, the Fischer indolization should proceed via a [3,3] sigmatropic route, with an electronic effect.