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Cycloadditions, 27 . The Thermal Rearrangement of the Bicyclo[2.2.2]‐ to Bicyclo[3.2.1]octadiene Moiety in Tricyclic Lactams
Author(s) -
Himbert Gerhard,
Diehl Klaus
Publication year - 1997
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199719970631
Subject(s) - moiety , bicyclic molecule , chemistry , intramolecular force , zwitterion , tricyclic , stereochemistry , lactam , medicinal chemistry , organic chemistry , molecule
The tricyclic lactams 4a–h , possessing a bicyclo[2.2.2]octadiene moiety, obtained by intramolecular Diels‐Alder reaction of the vinylidene malondiamides 1a–h , generally isomerize in boiling xylene to give the new lactams 7a–h , now bearing a bicyclo[3.2.1]octadiene part. The difference in the rates of the isomerizations 4 → 7 and the results with the nitro ‐ and methoxy‐substituted derivatives 4i–l are in accordance with the proposed intermediate zwitterion 6 , which is formed by the migration of one vinyl group from position 1 to position 5 of the lactam moiety.