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5‐Aminothiazolium Salts as Potential Cyclic Azomethine Ylides – Base‐Induced Intramolecular Cycloaddition Reactions of N ‐( o ‐Allylphenyl)‐ and N ‐( o ‐(Allyloxy)phenyl)‐Substituted Derivatives
Author(s) -
Morel Georges,
Marchand Evelyne,
Benjelloun Adile Touimi,
Sinbandhit Sourisak,
Guillou Olivier,
Gall Philippe
Publication year - 1998
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199811)1998:11<2631::aid-ejoc2631>3.0.co;2-w
Subject(s) - mesoionic , chemistry , cycloaddition , substituent , intramolecular force , ring (chemistry) , structural isomer , stereochemistry , olefin fiber , 1,3 dipolar cycloaddition , medicinal chemistry , organic chemistry , catalysis
A series of 5‐aminothiazolium chlorides ( 1 ) bearing tethered benzene ring on N‐3, C‐4 or the exocyclic nitrogen atom are prepared by a three‐component methodology and subjected to basic treatment. The initially generated mesoionic thiazoles 2 undergo internal 1,3‐dipolar cycloaddition across the pendant olefin when the 2‐allylphenyl group is connected to the endocyclic N‐3. The reaction leads to the formation of original N ‐bridged thiazoloquinolines as a mixture of two regioisomers 3 , 4 which are readily separated by chromatography. The structural assignments of the cycloadducts are deduced from their spectroscopic NMR properties and unequivocally established by an X‐ray diffraction analysis. Intramolecular sequence also occurs using the 2‐(allyloxy)phenyl substituent on the same position to give a single regioisomeric 1,4‐methanothiazolobenzoxazepine ( 7 ). On the contrary, hydrolysis and ring‐opening or oxidation and rearrangement of the mesoionic intermediates are the exclusive base‐promoted conversions of other thiazolium salts 1 .