A phosphine-free palladium-catalyst condition for the Heck reaction using dicyclohexylamine as ancillary ligand was investigated, establishing a new Heck reaction system using phosphine-free palladium-catalyst, which can synthesize di- and tri-substituted stilbene compounds in high yields (72%～84%) and high stereoselectivities (83%～95%). Four novel stilbene derivatives of arotinoic methyl ester (3a, 3b, 4a and 4b) were synthesized by above method using 2,4,5-trimethoxystyrene and α-asarone as starting materials. Their hydrolysates the arotinoic acids (5a, 5b, 6a and 6b) were easily accessible under mild hydrolysis conditions using the LiOH, THF/H₂O (V∶V＝5∶1) system, and all the structures of synthesized compounds were confirmed by ¹H NMR, ¹³C NMR, IR and MS techniques.

Key words: arotinoic acid, styrene derivative, stilbene, dicyclohexylamine, palladium, Heck reaction, LiOH