A compound according to formula (III): ** Formula ** the compound of formula (III) being selected from the group consisting of (i) compounds of formula (III) in which R1 is a halogen atom selected from Cl and F, R2-R6 are independently hydrogen, halogen, hydroxyl, C1-C4 alkyl, C1-C4 alkoxy, acyloxy, phenyl, benzyl, or - C (O) R7 in which R7 is C1-C4 alkyl, including salts and hydrates of these compounds, in which at least one of R2-R6 is other than hydrogen and R2-R6 includes no more than one acyloxy and no more than one halogen, and (ii) compounds of formula (III) in which R1 is Br, and (a) R2-R6 are independently hydrogen, halogen, hydroxyl, C1-C4 alkyl, C1-C4 alkoxy. acyloxy, phenyl, benzyl, or -C (O) R7 in which R7 is C1-C4 alkyl, including salts and hydrates of these compounds, in which at least one of R2-R6 is a hydroxyl in the ortho position of the benzene ring and R2-R6 includes no more than one acyloxy and no more than one halogen, or (b) R2 is OR8 where R8 is -C (O) R10, where R10 is C1-C4 alkyl, R3 is C1-C4 alkyl or C1-C4 alkoxy, and R4-R6 are hydrogen, including salts and hydrates of these compounds, or (c) R2-R6 are independently hydrogen, acyloxy, phenyl, benzyl, or -C ( O) R7 in which R7 is C1-C4 alkyl, including salts and hydrates of these compounds, in which at least two of R2-R6 are other than hydrogen.Un compuesto según la fórmula (III):**Fórmula** siendo seleccionado el compuesto de fórmula (III) del grupo que consiste en (i) compuestos de fórmula (III) en la que R1 es un átomo de halógeno seleccionado de Cl y F, R2-R6 son independientemente hidrógeno, halógeno, hidroxilo, alquilo de C1-C4, alcoxi de C1-C4, aciloxi, fenilo, bencilo, o - C(O)R7 en la que R7 es alquilo de C1-C4, incluyendo sales e hidratos de estos compuestos, en los que por lo menos uno de R2-R6 es distinto de hidrógeno y R2-R6 incluye no más de un aciloxi y no más de un halógeno, y (ii) compuestos de fórmula (III) en la que R1 es Br, y (a) R2-R6 son independientemente hidrógeno,
