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A Novel Approach towards 2,3,5‐Trisubstituted Thiophenes via tandem Michael addition/intramolecular Knoevenagel condensation
Author(s) -
Obrecht Daniel,
Gerber Fernand,
Sprengeir Daniel,
Masquelin Thierry
Publication year - 1997
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/hlca.19970800217
Subject(s) - chemistry , knoevenagel condensation , thiophene , intramolecular force , tandem , combinatorial chemistry , alcohol , condensation , molecule , organic chemistry , catalysis , materials science , physics , composite material , thermodynamics
Starting from the easily available, highly functionalized acetylenic ketories 4a–i ( Scheme 1 ), novel 2,3,5‐trisubstituted thiophenes 1a–i ( Scheme 2 ) were synthesized in good yields using a tandem Michael ‐addition/intramolecular Knoevenagel ‐condensation strategy, featuring Cs 2 CO 3 /MgSO 4 (1:2) as an efficient base to effect the cyclization. Subsequent simple one‐step transformations yielded 2,3‐disubstituted thiophene‐5‐carbaidehydes 7a–c , carboxylic‐acid derivatives 8, 9 , and 11 , and alcohol 10 ( Scheme 3 ). These molecules constitute interesting novel thiophene‐containing building blocks, useful for the preparation of low‐molecular‐weight compound libraries by combinatorial and parallel‐chemistry techniques.