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Methine‐Brigded Five‐Membered Heterocycles as Precursors for Low‐Gap Polymers
Author(s) -
Hieber Gunter,
Hanack Michael,
Wurst Klaus,
Strähle Joachim
Publication year - 1991
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19911240721
Subject(s) - chemistry , knoevenagel condensation , oxide , polymer , condensation reaction , polymer chemistry , medicinal chemistry , organic chemistry , stereochemistry , catalysis
The synthesis of suitable precursors of polyarenemethines (PAM) 1 , which are predicted to be potential low gap polymers, is described. The Knoevenagel condensation of heteroaromatic aldehydes with 2,5‐dihydrothiophene 1,1‐dioxide ( 5 ), 2,5‐dihydrothiophene 1‐oxide ( 9 ), and its benzo‐annulated analogs [ 6 and [ 10 ] yields the methine‐bridged compounds 7 , [ 8 ], 11 , and [ 12 ], respectively. Reduction of the methine‐bridged sulfoxides 11 and [ 12 ] leads to the corresponding sulfides 13 and [ 14 ]. For compound 18 with a high sterical demand another route has been developed. Thus, the reaction of the dicarbinol 17 with HI yields directly the heteroaromatic quinodimethane 18 . The molecular structures of 7a and 18 are determined by X‐ray analysis.