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Synthesis of new thiazolium betaines and the ring expansion reaction via 1,4‐dipolar cycloaddition
Author(s) -
Kim Dong Chan,
Kim Dong Jin,
Park Sang Woo,
Ho Yoo Kyung
Publication year - 1995
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570320528
Subject(s) - chemistry , cycloaddition , betaine , methyl iodide , ring (chemistry) , isothiocyanate , 1,3 dipolar cycloaddition , reactivity (psychology) , medicinal chemistry , iodide , alkylation , stereochemistry , organic chemistry , catalysis , medicine , alternative medicine , pathology
The 1,4‐dipolar cycloaddition of 3‐phenyl‐7‐[ N ‐pheny(carbamoyl)]‐5,6‐dihydroimidazo[2,1‐ b ]thia‐zolium betaine (7d) with a series of aliphatic alkylating agents such as ethyl bromoacetate, α‐chloroacetone, and ethyl 4‐chloroacetoacetate gave a variety of new ring‐expanded cycloadducts 10a‐c instead of ring transformation compounds 9 . This result was derived from the difference of reactivity between N ‐ and S ‐alkylations of thiazolium betaines 7a,d. The advantage of our method is to prepare the triheterocyclic compounds 10a‐c of complicated structure using reactive thiazolium betaine 7d in a one‐pot without isolation of intermediates. Treatment of N ‐bridged thiazolo compounds 1a‐c with benzoyl isothiocyanate led to new thiazolium betaines 2a‐c , which were reacted with methyl iodide to afford the S ‐alkylated quarternary ammonium salts 3a‐c. Synthesis of new 2‐iminothiazolinium betaines 5a,b also was carried out.