The use of a compound of the formula I wherein n is 1 to and including 6； W is O or S； R1 and R3 independently represent each other hydrogen, lower alkyl or lower acyl； R2 represents a cycloalkyl group, or an aryl group, or a mono or bicyclic heteroaryl group comprising one or more ring nitrogen atoms and 0, 1 or 2 heteroatoms independently of each other selected from the group consisting of oxygen and sulfur, whose groups in each case are unsubstituted or substituted by up to three substituents, selected from amino, mono or disubstituted amino, halogen, lower alkyl, substituted alkyl, lower alkenyl, lower alkynyl, lower alkanoyl, hydroxy, etherified or esterified hydroxy, nitro, cyano , carboxy, esterified carboxy, alkanoyl, benzoyl, carbamoyl, carbamoyl N-mono or N, N-disubstituted, amidino, guanidino, ureido, mercapto, sulfo, lower alkylthio, phenyl, phenoxy, phenylthio, phenyl-lower alkylthio, alkylphenylthio, alkylsulfinyl lower, phenylsulfinyl, phenyl-lower alkylsulfinyl, alkylphenylsulfinyl, lower alkanesulfonyl, phenylsulfonyl, lower phenylalkyl sulfonyl, alkylphenyl sulfonyl, halogen-lower alkyl mercapto, halogen-lower alkyl sulfonyl, dihydroxyboro (-B (OH) 2), heterocyclyl, and lower alkylene dioxy bonded to adjacent C atoms of the ring； R and R 'are independently of each other hydrogen or lower alkyl.El uso de un compuesto de la fórmula I en donde n es de 1 hasta e incluyendo 6； W es O o S； R1 y R3 representan independientemente uno del otro hidrógeno, alquilo inferior o acilo inferior； R2 representa un grupo cicloalquilo, o un grupo arilo, o un grupo heteroarilo mono o bicíclico que comprende uno o más átomos de nitrógeno del anillo y 0, 1 o 2 heteroátomos independientemente uno del otro seleccionados del grupo que consiste de oxígeno y azufre, cuyos grupos en cada caso están no sustituidos o sustituidos por hasta tres sustituyentes, seleccionados entre amino, amino mono o disustituidos, halógeno, alquilo inferior, alquilo sustituido, alquenilo inferior,
