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Regioselective Synthesis of 2‐Imino‐1,3‐thiazolidin‐4‐ones by Treatment of N ‐(Anthracen‐9‐yl)‐ N ′‐ethylthiourea with Bromoacetic Acid Derivatives
Author(s) -
Klika Karel D.,
Janovec Ladislav,
Imrich Ján,
Suchár Gejza,
Kristian Pavol,
Sillanpää Reijo,
Pihlaja Kalevi
Publication year - 2002
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 - 10.1002/1099-0690(200204)2002:7<1248::aid-ejoc1248>3.0.co;2-h
Subject(s) - regioselectivity , chemistry , electrophile , ring (chemistry) , bromide , stereochemistry , medicinal chemistry , organic chemistry , catalysis
The reaction between N ‐(anthracen‐9‐yl)‐ N′ ‐ethylthiourea ( 1 ) and methyl bromoacetate yielded mainly 2‐[(anthracen‐9‐yl)imino]‐3‐ethyl‐1,3‐thiazolidin‐4‐one ( 2 ), together with some of the regioisomeric 3‐(anthracen‐9‐yl)‐2‐ethylimino‐1,3‐thiazolidin‐4‐one ( 3 ). The structures of the products were elucidated by NMR techniques and, for 3 , X‐ray crystallographic analysis. Treatment of 1 with bromoacetyl bromide again yielded 2 and 3 , but with a reversed product distribution ratio, thus providing an interesting and unexpected regioselectivity, depending on the electrophile selected. The underlying cause of the observed regioselectivity is a result of different reaction pathways taken by the two electrophiles. The number of possible products, including those resulting from ring‐opening/ring‐closing rearrangements is large (24 in total), and a simple lettered notation is introduced to handle the set of structures conveniently. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)