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Inverse and Normal [4 + 2] Cycloadditions of a 4a,8a‐Methanophthalazine to Azirines and 1,2,4‐Triazoline‐3,5‐dione as Heterodienophiles
Author(s) -
Laue Jörg,
Seitz Gunther
Publication year - 1996
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.199619960427
Subject(s) - propellane , chemistry , cycloaddition , aziridine , yield (engineering) , molecule , selectivity , bicyclic molecule , stereochemistry , medicinal chemistry , organic chemistry , catalysis , physics , ring (chemistry) , thermodynamics
The 4a,8a‐methanophthalazine 4 is a novel propellane containing an electron‐rich cyclohexadiene and an electron‐deficient diazadiene system within the same molecule. The highly strained azirines 6 and 9a – c , prepared from the corresponding vinyl azides 5 and 8a – c , undergo cycloaddition in situ to the diazadiene system of 4 to furnish the stable polycyclic azo compounds 7c and 10 – 12 which possesses exo configuration at the annulated aziridine. Attack apparently occurs from the less hindered face, anti to the methano bridge of 4 with high stereo‐ and site selectivity. The electron‐deficient 1,2,4‐triazoline‐3,5‐dione 13 reacts with the electron‐rich diene of the azo compound 12 to yield the anti‐anti bisadduct 14 .