A racemate, diastereoisomer and optical isomer of a compound of formula (I):wherein B is H, a C6 or C10 aryl, C7-16 aralkyl； Het or (lower alkyl)-Het, all of which may be optionally substituted with C1-6 alkyl； C1-6 alkoxy； C1-6 alkanoyl； hydroxy； hydroxyalkyl； halo； haloalkyl； nitro； cyano； cyanoalkyl； amino optionally substituted with C1-6 alkyl； amido； or (lower alkyl)amide； orB is an acyl derivative of formula R4&mdash；C(O)&mdash；； a carboxyl derivative of formula R4&mdash；O&mdash；C(O)&mdash；； an amide derivative of formula R4&mdash；N(R5)&mdash；C(O)&mdash；； a thioamide derivative of formula R4&mdash；N(R5)&mdash；C(S)&mdash；； or a sulfonyl of formula R4&mdash；SO2； R5 is H or C1-6 alkyl； andY is H or C1-6 alkyl；R3 is C1-8 alkyl, C3-7 cycloalkyl, or C4-10 alkylcycloalkyl, all optionally substituted with hydroxy, C1-6 alkoxy, C1-6 thioalkyl, amido, (lower alkyl)amido, C6 or C10 aryl, or C7-16 aralkyl；R2 is CH2&mdash；R20, NH&mdash；R20, O&mdash；R20 or S&mdash；R20, wherein R20 is a saturated or unsaturated C3-7 cycloalkyl or C4-10 (alkylcycloalkyl), all of which being optionally mono-, di- or tri-substituted with R21,or R20 is a C6 or C10 aryl or C7-14 aralkyl optionally substituted, or R20 is Het or (lower alkyl)-Het, both optionally substituted, Het or (lower alkyl)-Het； carboxyl； carboxy(lower alkyl)； C6 or C10 aryl, C7-14 aralkyl or Het, said aryl, aralkyl or Het being optionally substituted； andR1 is H； C1-6 alkyl, C3-7 cycloalkyl, C2-6 alkenyl, or C2-6 alkynyl, all optionally substituted with halogen； or a pharmaceutically acceptable salt or ester thereof.Racemater, diastereoisomerer og optiske isomerer av en forbindelse av formel (I) hvor B er H, en C6 eller C10 aryl, C7-16 aralkyl； Het eller (lavere alkyl)-Het, hvorav alle eventuelt er substituert med C1-6alkyl； C1-C6alkoksy； C1-C6alkanoyl； hydroksy； hydroksy alkyl； halogen； halogenalkyl； nitro； cyano； cyanoalkyl； amino eventuelt substituert med C1-C6alkyl； amido； eller (lavere alkyljamid； eller B er et acylderi
