Oligomers of uniformly arranged chalcone building blocks

A convergent and coupled synthesis was developed for the cross-conjugated o ligomers 1a-d which contain one to four chalcone building blocks arranged i n the same direction. The preparation started with 1,4-dipropoxybenzene (2) and led via bromination (2 --> 3, 6) and Bouveault reactions to the carbon yl components 4, 5 and 7. Protection of the formyl group (7 --> 8) and a fu rther Bouveault reaction yielded the bifunctional compound 9 which played a central role for the extension of the chain. The substituted benzaldehyde 4 was transformed by this means to the aldehydes 10, 11 and 12. The compoun ds 4 and 10-12 reacted in the final step with the acetophenone 5 to the des ired oligomers 1a-d.