| abstract |
A compound of the formula ** Formula ** in which R1 is ** Formula ** R2 is hydrogen, 2,2-dimethyl-propionyloxymethyl or benzyl, in which benzyl is optionally substituted with one to two fluorine atoms, alkyl C1-C3 optionally substituted with 1 to 3 fluorine atoms, or C1-C3 alkoxy; R3 is hydrogen, 2,2-dimethyl-propionyloxymethyl or benzyl, in which benzyl is optionally substituted with one to two fluorine atoms, C1-C3 alkyl optionally substituted with 1 to 3 fluorine atoms, or C1-C3 alkoxy; R4 is hydrogen, (2S) -2-aminopropanoyl, (2S) -2-amino-4-methylsulfanyl-butanoyl, (2S) -2-amino-4-methylpentanoyl or 2-aminoacetyl; R5 is C1-C3 alkyl optionally substituted with 1 to 3 fluorine atoms, -NH2 or cyclopropyl; with the proviso that when R2 and / or R3 are not hydrogen, then R4 is hydrogen; with the proviso that when R4 is not hydrogen, then R and / or R are hydrogen; and with the proviso that R5 can be hydrogen when the sulfur atom is attached to the bicyclo [3.1.0] hexane ring system in the S configuration; or a pharmaceutically acceptable salt thereof. |