Formulas having the meanings indicated in claim 1 W, R, R 1, R 2, R 3, R 4, R 4 , R 5, R 5, R 6, R 6 , R 7 is and s can be employed in the treatment of tumors, especially a compound of formula (I).W、R、R1、R2、R3、R4、R4’、R5、R5’、R6、R6’、sおよびR7が請求項1に示された意味を有する式(I)の化合物を特に腫瘍の治療に採用することができる。