Process for preparing aromatic olefins by using palladaphosphacyclobutanes as catalysts

A process for preparing aromatic olefins of the formula (I)

• wherein
• R1a to R5a are, independently of one another, hydrogen, C1-C8-alkyl, C1-C8-alkoxy, C1-C8-acyloxy, O-phenyl, phenyl, fluorine, chlorine, bromine, OH, NO2, OSO2CF3, CN, COOH, CHO, SO3H, SO2R, SOR, NH2, NH—C1-C8-alkyl, N(C1-C8-alkyl)2, CHal3, NHCO—C1-C4-alkyl, N—C1-C4-alkyl-CO—C1-C4-alkyl, COO—C1-C8-alkyl, CONH2, CO—C1-C8-alkyl, NHCOH, NCOO—C1-C4-alkyl, CO-phenyl, COO-phenyl, CHCH—CO2—C1-C8-alkyl, CHCHCO2H, PO(phenyl)2, PO(C1-C4-alkyl)2, OSO2-phenyl or OSO2CH3, wherein one of the radicals R1a to R5a can also be
• wherein
• R6a is hydrogen, C1-C8-alkyl, phenyl, O—C1-C8-alkyl or fluorines;
• and
• R7a and R8a are, independently of one another, hydrogen, CN, CO2H, CO2—C1-C8-alkyl, CONH2, CONH—C1-C4-alkyl, CON(C1-C4-alkyl)2, fluorine, CO2-phenyl, C1-C8-phenyl, PO(phenyl)2, PO(C1-C4-alkyl)2, CO-phenyl, CO—C1-C4-alkyl, O—C1-C4-alkyl, NH—C1-C4-alkyl, PO3H, SO3H, SO3—C1-C4-alkyl, SO2—C1-C4-alkyl, O-phenyl or C1-C8-alkyl,
• by reacting haloaromatics of the formula (II)
• with olefins of the formula (III)
• wherein R1a to R8a are as defined above and X is as defined for R1a to R5a,
• wherein a palladium compound of the formula (IV)
• wherein
• R1, R2 are, independently of one another, hydrogen, C1-C4-alkyl, C3-C12-cycloalkyl, C1-C4-alkoxy, fluorine, N(C1-C4-alkyl)2, CO2—C1-C4-alkyl, OCO—C1-C4-alkyl or aryl;
• and
• R3, R4, R5, R6 are, independently of one another, C1-C8-alkyl, C3-C12-cycloalkyl or aryl;
• or wherein R1 and R2, R1 or R2 and R3 or R4, R3 and R4, R3 or R4 and R5 or R6, R5 and R6 together form an aliphatic ring having from 4 to 10 carbon atoms,
• or wherein R5 and R6, R3 or R4 and R5 or R6 together form an aromatic ring having from 5 to 9 carbon atoms, and
• Y is an anion of an inorganic or organic acid, is used as catalyst.