A compound of formula (I)wherein n is 0 to 4； m is 0 or 1 with the proviso that the sulphur atom and R3are in vicinal position (if m = 0 then R3is in position 2', and if m = 1 then R3is on position 1')； R is ethyl or vinyl； R1is hydrogen or (C1-6)alkyl, R2is 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 R1and R2together 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 R1is hydroxy and R2is formyl； R3is OH, OR4, a halogen atom, or - with the proviso that R3is bound to 2'R3represents -O-(CH2)p-O- with p is 2 or 3； R4is unsubstituted (C1-6)alkyl or (C3-6)cycloalkyl.一種式(I)之化合物其中n為0至4；m為0或1，惟硫原子與R3呈鄰位(若m=0則R3於位置2’，及若m=1則R3於位置1’)；R為乙基或乙烯基；R1為氫或(C1-6)烷基；R2為氫或-(C3-6)環烷基，或-未經取代的(C1-6)烷基，或-經以下之一者或多者取代的(C1-6)烷基-羥基；較佳為一個或兩個，-甲氧基，-鹵素，-(C3-6)環烷基，或R1及R2與其附接的氮原子一起形成至少含有一個氮原子或一個氮原子及一個例如選自N或O之另外的雜原子之5至7員雜環，或R1為羥基及R2為甲醯基；R3為OH、OR4、鹵原子，或-惟R3接合至2’，R3表示-O-(CH2)p-O-，其中p為2或3；R4為未經取代的(C1-6)烷基或(C3-6)環烷基。
