Synthesis of three new donor- acceptor [4] dendralenes

Three new donor - acceptor [4] dendralene compounds have been synthesized. Wittig reaction was used for the preparation of first two compounds and third one by Knoevehagel condensation. Their mass was calculated by APCI mass spectra which are in good agreement with theoretical data. UV-Vis data indicate the cross- conjugation in these systems due to the push-pull intra molecular charge transfer (CIT) sequence from electron donor to acceptor group. The 1H-NMR signals appear in aromatic region confirming the formation of trans (having π- structures) isomers rather than cis may be due to the exposure of the compounds to ambient light. The dominating roll of electron acceptor nitro, methoxy and cyno benzene groups in conjugation is clearly shown. The 13CNMR spectra which also supported the above analytical data and the number of carbons atoms obtained representing well the structures established.