Patent ID: 6846810

Claim:
A compound of formula I wherein: R 1 and R 2 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 3 and R 4 are independently selected from the group consisting of hydrogen COR 5 , C(═O)OR 5 , C(═O)SR 5 and COCH(R 6 )NHR 7 ; or, R 3 and R 4 taken together are selected from the group consisting of CH 2 , C(CH 3 ) 2 and CHPh; 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, alkyl substituted C 3-8 cycloalkyl phenyl, phenyl optionally substituted with one to three substituents independently selected from the group consisting of halo, lower alkyl, lower alkoxy, lower thioalkyl, lower alkyl sulfinyl, lower alkyl sulfonyl, nitro, 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, R 5 OCO; or, R 6 and R 7 taken together are (CH 2 ) 3 ; and, hydrates, solvates, clathrates and acid addition salts thereof; with the proviso that at least one of R 1 , R 2 , R 3 , or R 4 is other than hydrogen.