Fischer indolization of ethyl pyruvate 2-[2- (trifluoromethyl)phenyl]phenylhydrazone and new insight into the mechanism of the Goldberg reaction. (Fischer indolization and its related compounds. XXVI)

Article abstract of DOI:10.1248/cpb.43.1281

The Fischer indolization of ethyl pyruvate 2-[2- (trifluoromethyl)phenyl]phenylhydrazone (5) gave two indolic products, ethyl 7-(trifluoromethyl)-1-phenylindole-2-carboxylate (12) as a minor product and ethyl 1-[2-(trifluoromethyl)phenyl]indole-2-carboxylate (13) as a major product. This result shows that the Fischer indolization occurred on the more electron-rich phenyl group. In the Goldberg reaction to prepare 13 from ethyl indole-2-carboxylate (15) and o- (21) or m-bromo-α,α,α-trifluorotoluene (23), it was found that Goldberg reaction proceeds via a benzyne mechanism, at least in part, in a sterically crowded situation.

Full text of DOI:10.1248/cpb.43.1281

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