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The synthesis of medium‐sized cyclic lactams by the intramolecular friedel‐crafts cyclization of isocyanates. Formation of novel pyrazolo[3,4‐ c ]benzolactams
Author(s) -
Butler Donald E.,
Alexander Susan M.
Publication year - 1982
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.5570190537
Subject(s) - chemistry , methylhydrazine , lactam , intramolecular force , yield (engineering) , ring (chemistry) , friedel–crafts reaction , stereochemistry , medicinal chemistry , organic chemistry , catalysis , metallurgy , phenylhydrazine , materials science
A series of 4‐ω‐phenylalkyl substituted‐1 H ‐pyrazol‐5‐amines has been synthesized from the corresponding α‐acetylphenylalkanenitriles and methylhydrazine. They were converted into the corresponding 5‐isocyanates and cyclized under Friedel‐Crafts conditions to medium‐sized cyclic lactams. The reaction was shown to give the 7‐, 8‐, 9‐, and 10‐membered lactams but failed to yield the 11‐membered lactam. Rings synthesized were: pyrazolo[3,4‐ c ][2]benzazepin‐2(1 H )‐one; 10 H ‐pyrazolo[3,4‐ c ][2]benzazocin‐10‐one; pyrazolo[3,4‐ c ][2]benzazonin‐11(1 H )‐one; 12 H ‐pyrazolo[3,4‐ c ][2]benzazocin‐12‐one.