Patent ID: 7378402

Claim:
A compound of formula I wherein: R 1 , R 2 , R 3 , and R 4 are independently selected from the group consisting of hydrogen, COR 5 , C(═O)OR 5 , C(═O)SR 5 , C(═O)NHR 5 and COCH(R 6 )NHR 7 ; R 5 is independently selected from the group consisting of C 1-18 unbranched or branched alkyl, C 1-18 unbranched or branched alkenyl, C 1-18 unbranched or branched alkynyl, C 1-18 lower haloalkyl, C 3-8 cycloalkyl, C 3-8 cycloalkyl-C 1-3 alkyl, phenyl optionally substituted with one to three substituents independently selected from the group consisting of halo, C 1-6 alkyl, C 1-6 lower alkoxy, C 1-6 lower thioalkyl, C 1-6 lower alkyl sulfinyl, C 1-6 lower alkyl sulfonyl, nitro and cyano, CH 2 Ph wherein in phenyl ring is optionally substituted as described above, and CH 2 OPh wherein in phenyl ring is optionally substituted as described above; R 6 is independently selected from the group consisting of the side chains of naturally occurring amino acids and C 1-5 unbranched or branched alkyl; R 7 is selected from the group consisting of hydrogen and R 5 OCO; or, R 6 and R 7 taken together are (CH 2 ) 3 ; and, acid addition salts thereof.