Ishii, Hisashi published the artcileFischer indolization and its related compounds. XXIV. Fischer indolization of ethyl pyruvate 2-(2-methoxyphenyl)phenylhydrazone, COA of Formula: C12H13NO3, the publication is Chemical & Pharmaceutical Bulletin (1991), 39(3), 572-8, database is CAplus.
In order to clarify the mechanism of Fischer indolization of 2-methoxyphenylhydrazones, Fischer indolization of Et pyruvate 2-(2-methoxyphenyl)phenylhydrazone I was carried out with hydrochloric acid in ethanol and zinc chloride in acetic acid. The reactions proceeded smoothly to give N-arylindoles II (R = Ph, R1 = R2 = H; R1 = Cl, R2 = H; R1 = H, R2 = OMe; R = 2-MeOC6H4, R1 = R2 = H) and some chlorinated diphenylamine derivatives III (R3 = Cl, R4 = R5 = H; R3 = R5 = H, R4 = Cl; R3 = R4 = H, R5 = Cl, R3-R5 = H) as byproducts. Consideration of the indole products revealed that the Fischer indolization proceeded mainly at the unsubstituted Ph nucleus rather than at the 2-methoxyphenyl nucleus. This result is inconsistent with the previous result that Fischer indolization of diarylhydrazones proceeded at the electron-richer nucleus. The structures of the diphenylamines III were determined by chem. means and the mechanism of their formation is discussed.
Chemical & Pharmaceutical Bulletin published new progress about 20538-12-9. 20538-12-9 belongs to indole-building-block, auxiliary class Indole,Ester,Ether, name is Ethyl 7-methoxy-1H-indole-2-carboxylate, and the molecular formula is C12H13NO3, COA of Formula: C12H13NO3.
Referemce:
https://www.nature.com/articles/s41429-020-0333-2,
Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles