The present invention provides a compound of Formula (I) (structurally represented) wherein R1 is H or C1-6 alkyl, R2 is H or C1-6 alkyl or CH20H, R3 is H or C1-6 alkyl, and R4 is H or C1-6 alkyl, provided that when R1, R2, and R3 are H, R4 is C1-6 alkyl, and when R1, R2, and R4 are H, then R3 is C1-6 alkyl, and when R1, R3, and R4 are H, R2 is C1-6 alkyl or-CH20H, and when R2, R3, and R4 are H, then R1 is C 1-6 alkyl； A is 1 ) a 9-10 membered bicyclic heterocycle having 1-3 heteroatoms independently selected from N, S and 0, which 9-10 membered bicyclic heterocycle is unsubstituted or substituted with R5 and unsubstituted or substituted with R6 and unsubstituted or substituted with NH2, or 2) a 6-9 membered monocyclic or bicyclic carbocyclic ring system unsubstituted or substituted with R5, unsubstituted or substituted with R6, and unsubstituted or substituted with -CH2NH2； and B is 1) a 5- or 6-membered monocyclic heterocycle having 1 or 2 heteroatoms independently selected from N, S or 0, which is unsubstituted or substituted on a carbon or nitrogen atom with R7, unsubstituted or substituted on a carbon or nitrogen atom with R8, and unsubstituted or substituted on a carbon or nitrogen atom with R9, or 2) an 8- or 9-membered fused bicyclic heterocycle having 1, 2 or 3 nitrogen atoms which is unsubstituted or substituted on a carbon or nitrogen atom with R7, and unsubstituted or substituted on a carbon or nitrogen atom with R8； and pharmaceutical compositions comprising one or more said compounds, and methods for using said compounds for treating or preventing thromboses.La présente invention concerne un composé de la formule (I) (représentée structurellement), dans laquelle R1 représente H ou alkyle en C1-6, R2 représente H ou alkyle en C1-6 ou CH2OH, R3 représente H ou alkyle en C1-6 et R4 représente H ou alkyle en C1-6, à condition que lorsque R1, R2 et R3 représentent H, R4 désigne alkyle en C1-6 et que lorsque R1, R2 et R4 représentent H, R3 désigne alors alky
