to the present invention r u2033 is preferably the side chain of a natural amino acid and in particular ala asn asp cys gly gln glu his ile leu lys met phe pro ser thr tyr try val at least one of x and y is halogen r 1 r 3 are methoxy and r is hydroxy at least one of x and y is halogen r 1 r 3 are methoxy r is amino or substituted amino at least one of x and y is halogen r 1 r 3 are different from methoxy r is hydroxy processes for the preparation of the compounds of the present invention shall be described in details by making reference to the synthetic schemes appended as figures the compounds of the present invention can be prepared by conventional synthetic methods however in some preferred embodiments of the present invention the starting compound is a compound of formula i wherein both x and y are hydrogen a process for the preparation of compounds of formula i wherein x and y are both f comprises the following steps a reaction of 1 bromo 1 2 difluoro 2 4 methoxy 3 protected oh phenyl ethene with 3 r 1 4 r 2 5 r 3 phenylboronic acid and for step a 1 bromo 1 2 difluoro 2 4 methoxy 3 protected oh phenyl ethene can be obtained by synthetic methods available in the art for example isovanillin.