Patent ID: 8907126

Claim:
A tyrosine derivative of the following formula (I): wherein R 1 is a hydrogen atom or a protective group for the amino group; R 2 is a hydrogen atom or a protective group for the carboxy group; R 3 is a hydrogen atom or a C 1-6 alkyl group; R 4 is a halogen atom, a hydroxy group, a C 1-6 alkyl group, a C 1-6 halogenated alkyl group, an amino group, a mono(C 1-6 alkyl)amino group, a di(C 1-6 alkyl)amino group, an aryl group optionally having substituent α, a heterocyclic group optionally having substituent α, a C 1-6 alkoxy group, a C 1-6 alkylthio group, a C 1-6 halogenated alkoxy group or a C 7-13 aralkyloxy group optionally having substituent α; A is —(CH 2 ) l —[Z(CH 2 ) m ] n — wherein Z is an amino group, an ether group, a thioether group, a carbonyl group, a thionyl group, an ester group, an amide group, a urea group or a thiourea group; l is an integer of not less than 1 and not more than 6; m is an integer of not less than 1 and not more than 4; and n is an integer of not less than 0 and not more than 4; X is a leaving group selected from the group consisting of a chlorine atom, a bromine atom, an iodine atom, a methanesulfonyloxy group, a trifluoromethanesulfonyloxy group, a chloromethanesulfonyloxy group, an ethanesulfonyloxy group, a benzenesulfonyloxy group and a toluenesulfonyloxy group; substituent α is one or more substituents selected from the group consisting of a halogen atom, a hydroxy group, a cyano group, a thiol group, an amino group, a mono(C 1-6 alkyl)amino group, a di(C 1-6 alkyl)amino group, a C 1-6 alkyl group, a C 1-6 alkoxy group, a C 1-6 halogenated alkyl group and a C 1-6 alkylthio group; provided that the position of R 4 is para to the position of the X-A-O— group.