6533b7d4fe1ef96bd126272d

RESEARCH PRODUCT

Oligomere aus gleichsinnig angeordneten Chalkon-Bausteinen

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description

The cross-conjugated oligomers 1a–d, which contain up to eight alternately arranged chalcone building blocks, were prepared by stereoselective condensation reactions of formyl and acetyl components. The synthetic sequence started with 1,4-dibromo-2,5-dipropoxybenzene (2). Bouveault reactions with DMF and DMA yielded the aldehydes 3 and 6 and the ketones 7 and 10. After the protection of the carbonyl group (3 4 and 7 8), a further Bouveault reaction led to monoprotected dialdehyd 5 and diketone 9, respectively. Repetitive condensation reactions starting with the acetophenone derivative 11 and 5 furnished the aldehyde 12, the ketone 13 and the aldehyde 14. In the final step the target compounds 1 were obtained again by condensation reactions: 6 + 11 1a, 10 + 12 1b, 6 + 13 1c, 10 + 14 1d. Thus a convergent and coupled synthesis was achieved in order to generate constitutionally and configurationally pure oligochalcones.