Method for synthesizing pyrazolobenzodiazepines

A method of making a compound of formula I

• comprising
• (a) reacting a compound of formula
• with hydrazine;
• and
• (b) oxidizing the resulting dihydropyrazole to a pyrazole;
• wherein:
• R1 is selected from the group consisting of
• —H,
• —NO2,
• —CN,
• -halogen,
• -lower alkyl which is straight-chained and which optionally may be substituted by the group consisting of —OH and halogen,
• —OR5,
• —R6OR7,
• —COOR7,
• —CONR8R9,
• —NR10R11,
• —NHCOR12, and
• —NHSO2R13;
• R2 and R4 are each independently selected from the group consisting of
• —H,
• -halogen,
• —NO2,
• —CF3, and
• -straight chained lower alkyl;
• R3 selected from the group consisting of
• —H,
• -lower alkyl which optionally may be substituted by —OH,
• —OR9, F, and aryl,
• -cycloalkyl,
• -aryl,
• -heterocycle,
• -heteroaryl,
• —COOR7
• —CN,
• -alkenyl,
• —CONR8R9, and
• -alkynyl;
• R5 selected from lower alkyl which optionally may be substituted by halogen;
• R6 is selected from lower alkylene;
• R7 is selected from the group consisting of —H and lower alkyl;
• R8 and R9 are each independently selected from the group consisting of —H and -lower alkyl which itself optionally may be substituted by —OH and —NH2;
• alternatively, R8 and R9 may form a 5- or 6-membered heterocycle which optionally may be substituted by the group consisting of —OH, —NH2, and lower alkyl;
• R10, R11 and R12 are each independently selected from the group consisting of —H and lower alkyl;
• R13 is selected from the group consisting of lower alkyl which optionally may be substituted by the group consisting of halogen and —NR14R15;
• and
• R14 and R15 are each independently selected from the group consisting of —H and lower alkyl which optionally may be substituted halogen, or alternatively, —NR14R15 is a heterocycle.