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1,3‐Dipolar Cycloadditions with the Keto‐ and Spirocyclopropane‐Substituted Norbornenes Bicyclo[2.2.1]hept‐5‐en‐2‐one and Spiro[bicyclo[2.2.1]hept‐5‐ene‐2,1′‐cyclopropane]
Author(s) -
Adam Waldemar,
Carballeira Nestor,
Crämer Elisabeth,
Lucchini Vittorio,
Peters EvaMaria,
Peters Karl,
Schnering Hans Georg Von
Publication year - 1987
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19871200506
Subject(s) - chemistry , bicyclic molecule , regioselectivity , cycloaddition , diazomethane , structural isomer , cyclopropane , stereochemistry , 1,3 dipolar cycloaddition , medicinal chemistry , ring (chemistry) , organic chemistry , catalysis
The keto‐ and spirocyclopropane‐substituted norbornenes K and S , respectively, were submitted to 1,3‐dipolar cycloaddition with diazomethane ( 1 ), diphenyldiazomethane ( 2 ), phenyl azide ( 3 ), and benzonitrile oxide ( 4 ) leading in equal proportions to the corresponding regioisomers of the cycloadducts K‐2a, b through K‐4a, b and S‐1a, b through S‐4a, b . The keto and spirocyclopropane substituents perturb the π systems of these norbornenes too weakly to sense any significant regioselectivity for the 1,3‐dipoles employed here. A combination of NOE differential 1 H‐NMR spectroscopy and X‐ray analysis was essential to assign the structures of these regioisomers.