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[4 + 2] Cycloaddition Reactions of a 4a,8a‐Methanophthalazine with Electron‐Rich Alkynes: A New Synthesis of Substituted 1,6‐Methano[10]annulenes
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.199619960521
Subject(s) - cycloaddition , chemistry , annulene , aryne , moiety , propellane , pyridazine , alkyne , diacetylene , triptycene , phthalazine , selectivity , derivative (finance) , stereochemistry , photochemistry , medicinal chemistry , bicyclic molecule , organic chemistry , polymer , polymerization , catalysis , financial economics , economics
The novel propellane 3 containing an electron‐rich cyclohexadiene and an electron‐deficient diazadiene system in one and the same molecule reacts site selectively with the electron‐rich alkynes 4 and 8 as well as with cyclooctyne ( 10 ) to yield the interestingly substituted novel 1,6‐methano[10]annulenes 7 , 9 , and 11 . In contrast to this course of reaction, benzyne ( 12 ) undergoes a cycloaddition with the cyclohexadiene moiety of 3 with high site selectivity anti to the methano bridge to furnish the pentacyclic pyridazine derivative 14 . Interestingly benzyne ( 12 ) is able to react with the diazadiene system of the phthalazine 17 to form the triptycene 19 via the azo compound 18 .