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[3 + 5]‐Anellierung mit Homophthalaldehyd: Schlüsselreaktion zur Gewinnung zentral wirksamer Tricyclen
Author(s) -
Wünsch Bernhard,
Zott Matthias,
Höfner Georg
Publication year - 1992
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.1992199201204
Subject(s) - chemistry
[3 + 5] Annulation with Homophthalaldehyde: Key Step in the Synthesis of Central Active Tricycles [3 + 5] Annulation of the dinucleophile 11 with homophthalaldehyde ( 9 ) or homophthalaldehyde monoacetal 10 yielded regioselectively the β‐keto ester 12 . The tricyclic ketone 4 , obtained by saponification and decarboxylation of 12 , was reductively aminated with dimethylamine/NaBH 3 CN to give the tricyclic amines 5a and 5b . The ketone 4 was transformed into the 1,2‐amino alcohol 17 by Neber rearrangement as the key step. Schmidt rearrangement of 4 followed by LiAlH 4 reduction afforded the regioisomeric epoxybenzazonines 20a and 21a . In the mouse writhing test 21a and 5b exhibited strong analgesic effects with ED 50 values in the range of those of pethidine and tramadol.