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Benzo[ b ]thiophene derivatives. XXV. Condensation and reductive alkylation of 3‐aminoalkylbenzo[ b ]thiophenes with formaldehyde
Author(s) -
Campaigne E.,
Homfeld E.
Publication year - 1979
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570160706
Subject(s) - chemistry , thiophene , formaldehyde , alkylation , formic acid , pyridine , medicinal chemistry , organic chemistry , condensation , condensation reaction , catalysis , physics , thermodynamics
The reductive alkylation of 3‐aminomethylbenzo[ b ]thiophene by the Eschweiler‐Clarke (formaldehyde‐formic acid) method and of 3‐β‐aminoethylbenzo[ b ]thiophene by the Borch (formaldehyde‐cyanoborohydride) method proceeded in good yields. However, the Eschweiler‐Clarke reaction with 3‐β‐aminoethylbenzo[ b ]thiophene gave the Pictet‐Spengler cyclized product, N ‐methyl‐1,2,3,4‐tetrahydrobenzo[ b ]thieno[2,3 c ]pyridine. Mechanistic aspects of the latter reaction were investigated.