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Thermal rearrangement of 1,3‐thiazolidine sulfoxides: Thiolsulfinate and thioaldehyde intermediates
Author(s) -
Hahn HohGyu,
Nam Kee Dal,
Mah Heduck
Publication year - 1999
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.5570360141
Subject(s) - sulfenic acid , chemistry , nucleophile , sulfinic acid , sulfoxide , stereospecificity , electrophile , thiazolidine , medicinal chemistry , methoxide , ketenimine , acid catalysis , stereochemistry , catalysis , organic chemistry , cysteine , enzyme
Stereospecific ring opening of the sulfoxides cis ‐ 13 and trans ‐ 14 in refluxing toluene gave the corre sponding sulfenic acids 9 , 10 intermediates respectively. The sulfenic acid 9 dimerized to the thiolsulfinate 17 by dual function of the sulfenic acid as S ‐nucleophile/ S ‐electrophile with loss of water while the sulfenic acid 10 was unchanged. The stereospecific recyclization of 10 to the parent sulfoxide 14 increases the higher pi‐electron density of the double. The thermolysis of the thiolsulfinate 17 gave the transient sulfenic acid 9 , which dimerized again to repeat the process and unisolable thioaldehyde 21 . The thioaldehyde 21 was con verted to either pyrrole 15 by the action of a sulfinic acid 20 catalyst formed inevitably by hydrolysis of 17 under the reaction conditions, or thiazole 18 under neutral conditions. In these rearrangements, the amide carbonyl group facilitated the elimination of a neighboring hydrogen.