Process for preparing aryl- or heteroarylhexadienoic acids

DETAILED DESCRIPTION We claim: 1.
A process for preparing aryl- or heteroarylhexadienoic acids, characterized in that an aryl- or heteroarylacetylene of formula: R--C.
tbd.
CH (I), wherein R is an aryl group containing 1 or 2 rings or a heteroaryl group containing 1 or 2 rings and 1 to 2 heteroatoms selected from O, N, and S, in the radical, optionally substituted by substituents inert under the reaction conditions, and selected from halogen and alkyl, alkoxyl and carboalkoxy groups containing from 1 to 4 carbon atoms said aryl or heteroaryl acetylene containing a total of up to 20 carbon atoms, is reacted with 3-butenoic acid CH.
sub.
2 .
dbd.
CH--CH.
sub.
2 --COOH (II), in an alcoholic medium and in an inert atmosphere, at a temperature approximately maintained between 50.
degree.
C.
and 120.
degree.
C.
, at atmospheric pressure, in the presence of a catalyst selected from the group consisting of the phosphinic complexes of rhodium having the formulas: Rh(PR'.
sub.
3).
sub.
n L.
sub.
m X (III) associated with alkaline salts of carboxylic acids having up to 4 carbon atoms, and Rh(PR'.
sub.
3).
sub.
n L.
sub.
p.
sup.
+ Y.
sup.
- (IV) wherein R' is a hydrocarbyl group having up to 12 carbon atoms; L is a linear or cyclic olefin selected from the olefins having a number of carbon atoms of from 2 to 10 and the chelating olefins having 6 to 8 carbon atoms, n is an integer from 1 to 3, m is an integer from 0 to 2 and such that n+m= 2 or 3, and p is an integer from 0 to 3 and such that n+p=3 or 4; X is an anion selected from the haloid anions and the anions of carboxylic acids having up to 4 carbon atoms, and Y is a sparingly coordinating anion.
2.
The process of claim 1 in which the anion X is the hydrochloric anion.
3.
The process of claim 1 in which the sparingly coordinating anion Y is PF.
sub.
6.
sup.
- or BF.
sub.
4.
sup.
-.
4.
The process of claim 1, in which the alcoholic medium is an aliphatic alcohol having up to 5 carbon atoms.
5.
The process of claim 4, in which the alcoholic medium is ethyl alcohol.
6.
The process of claim 4 or 5, in which the alcoholic medium is employed in association with up to about 20% by weight of water