Kim, D.J. Yoo, K.H. Park, S.W. 2024-01-21T23:12:17Z 2024-01-21T23:12:17Z 2022-01-28 1992-01 0022-3263 https://pubs.kist.re.kr/handle/201004/146482 5,6-Dihydroimidazo[2,1-b]thiazolium betaines were generated in situ from 3,7-disubstituted 5,6-dihydroimidazo[2,1-b]thiazolium bromides and triethylamine. The reaction of these imidazothiazolium betaines with acetylenic dipolarophiles, such as ethyl propiclate, dimethyl acetylenedicarboxylate, and dibenzoylacetylene, provided geometric cis,trans isomers containing 2,3-dihydro-1H-pyrrolo[1,2-a]imidazole. We have proposed a mechanism of this reaction that involves 1,3-dipolar cycloaddition, isomeric rearrangement, and then nucleophilic addition successively. The ratio of trans and cis isomers depended on the temperature and solvents. The stereoselectivity of trans isomers increased with increasing temperature and decreasing polarity of solvents. ？ 1992, American Chemical Society. All rights reserved. English 1,3-Dipolar Cycloaddition of 5,6-Dihydroimidazo[2,1-b]thiazolium Betaines Article 10.1021/jo00034a029 1 Journal of Organic Chemistry, v.57, no.8, pp.2347 - 2352 Journal of Organic Chemistry 57 8 2347 2352 scopus 2-s2.0-0006205498 Article 5,6-dihydroimidazo[2,1-b]thiazolium betaines acetylenic dipolarophiles 1,3-dipolar cycloaddition geometric trans and cis isomers pyrrolo[1,2-a]imidazole