ALK2 inhibitors and methods for inhibiting BMP signaling

A compound of formula (I):

• or a pharmaceutically acceptable salt and/or prodrug thereof, wherein
• A1 is NR4a or CR4bR5;
• B1 is N or CR2;
• Z1 is N or CR3;
• R1 is selected from cycloalkyl, aryl, heteroaryl, and heterocyclyl;
• R2 is H, CN, NO2, alkyl, or amino;
• R3 is selected from H, CN, NO2, alkyl, alkoxy, heterocyclyloxy, heteroaryloxy, aryloxy, cycloalkyloxy, carbonyl, amino, amido, sulfonyl, sulfonamido, cycloalkyl, aryl, heterocyclyl, and heteroaryl;
• R4a is selected from alkyl, alkenyl, alkynyl, carbonyl, O−, alkoxycarbonyl, cycloalkyl, aryl, heterocyclyl, and heteroaryl;
• R4b is selected from halo, CN, NO2, hydroxy, alkyl, alkenyl, alkynyl, alkoxy, heterocyclyloxy, heteroaryloxy, aryloxy, cycloalkyloxy, amino, amido, carbonyl, alkoxycarbonyl, carboxy, sulfonyl, sulfonamido, thio, cycloalkyl, aryl, heterocyclyl, and heteroaryl;
• R5 is selected from H, halo, hydroxy and alkyl, or
• R4b and R5 together with A1 form a ring selected from cycloalkyl and heterocyclyl;
• each R6 is independently selected from H, halo, CN, NO2, hydroxy, alkyl, alkenyl, alkynyl, alkoxy, heterocyclyloxy, heteroaryloxy, aryl oxy, cycloalkyloxy, amino, amido, carbonyl, alkoxycarbonyl, carboxy, sulfonyl, sulfonamido, thio, cycloalkyl, aryl, heterocyclyl, and heteroaryl and oxo;
• n is 0 or 1;
• m is 0 or 1;
• and
• x is 0, 1, 2, 3, or 4.