A compound of formula (I) wherein n is 0 to 4 m is 0 or 1 with the proviso that the sulphur atom and R3 are in vicinal position (if m = 0 then R3 is in position 2�, and if m = 1 then R3 is on position 1�) R is ethyl or vinyl R1 is hydrogen or (C1-6)alkyl, R2 is hydrogen or -(C3-6)cycloalkyl, or - unsubstituted (C1-6)alkyl, or -(C1-6)alkyl substituted by one or more of - hydroxy preferably one or two, - methoxy, - halogen, -(C3-6)cycloalkyl, or R1 and R2 together with the nitrogen atom to which they are attached form a 5 to 7 membered heterocyclic ring containing at least 1 nitrogen atom or 1 nitrogen and 1 additional heteroatome e. g. selected from N or O, or R1 is hydroxy and R2 is formyl........
