Abstract: Compounds of formula I ##STR1## wherein X and Y each denotes hydrogen or together denote -0-,R.sub.1 denotes allyl optionally substituted by 1 to 3 alkyl groups, the substituent or substituents having in total a maximum of 3 carbon atoms, cyclopropyl-methyl or 3-furylmethyl,R.sub.2 denotes hydrogen, alkyl with 1 to 10 C-atoms, cycloalkyl with 5 or 6 carbon atoms, optionally substituted phenyl or optionally substituted phenyl-alkyl with 7 to 12 C-atoms,R.sub.3 denotes hydrogen, alkyl with 1 to 10 C-atoms or phenyl,R.sub.4 denotes hydrogen, OH, NR.sub.6 R.sub.7, NHCOR, NHSO.sub.2 R' or NHCOOR",R.sub.6 and R.sub.7, independently of one another, denote hydrogen or alkyl with 1 to 3 C-atoms,R denotes alkyl with 1 to 6 C-atoms, phenyl or --A--COOR",A denotes alkylene or alkenylene each with 2 to 4 C-atoms,R' denotes alkyl with 1 to 6 C-atoms or phenyl,R" denotes methyl or ethyland wherein either R.sub.3 is in the .alpha.-positionand R.sub.4 is in the .beta.-position, or R.sub.3 is in the .beta.position and R.sub.