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1,3‐Thiazolidine‐dicarboxylates from Thioketones and Thermally Generated Azomethine Ylides
Author(s) -
Mlostoń Grzegorz,
Urbaniak Katarzyna,
Heimgartner Heinz
Publication year - 2002
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(200207)85:7<2056::aid-hlca2056>3.0.co;2-o
Subject(s) - chemistry , thiazolidine , aziridine , isomerization , medicinal chemistry , cis–trans isomerism , ylide , fluorene , stereochemistry , ring (chemistry) , organic chemistry , catalysis , polymer
The reaction of 9 H ‐fluorene‐9‐thione ( 1 ) with the cis ‐ and trans ‐isomers of dimethyl 1‐(4‐methoxyphenyl)aziridine‐2,3‐dicarboxylate ( cis ‐ and trans ‐ 2 , resp.) in xylene at 110° yielded exclusively the spirocyclic cycloadduct with trans ‐ and cis ‐configurations, respectively ( trans ‐ and cis ‐ 3 , resp.; Scheme 1 ). Analogously, less‐reactive thioketones, e.g. , thiobenzophenone ( 5 ), and cis ‐ 2 reacted stereoselectively to give the corresponding trans ‐1,3‐thiazolidine‐2,4‐dicarboxylate ( e.g., trans ‐ 8 ; Scheme 2 ). On the other hand, the reaction of 5 and trans ‐ 2 proceeded in a nonstereoselective course to provide a mixture of trans ‐ and cis ‐substituted cycloadducts. This result can be explained by an isomerization of the intermediate azomethine ylide. Dimethyl 1,3‐thiazolidine‐2,2‐dicarboxylates 14 and 15 were formed in the thermal reaction of dimethyl aziridine‐2,2‐dicarboxylate 11 with aromatic thioketones ( Scheme 3 ). On treatment of 14 and 15 with Raney ‐Ni in refluxing EtOH, a desulfurization and ring‐contraction led to the formation of azetidine‐2,2‐dicarboxylates 17 and 18 , respectively ( Scheme 4 ).