Compounds, pharmaceutical compositions, and methods of preparing compounds and of their use as atr kinase inhibitors

A compound of formula (I):

• or a pharmaceutically acceptable salt thereof,
• wherein
• is a double bond, and each Y is independently N or CR4;
• or is a single bond, and each Y is independently NRY, carbonyl, or C(RY)2;
• wherein each RY is independently H or optionally substituted C1-6 alkyl;
• R1 is optionally substituted C1-6 alkyl or H;
• R2 is optionally substituted C2-9 heterocyclyl, optionally substituted C1-6 alkyl, optionally substituted C3-8 cycloalkyl, optionally substituted C2-9 heterocyclyl C1-6 alkyl, optionally substituted C6-10 aryl, optionally substituted C1-9 heteroaryl, optionally substituted C1-9 heteroaryl C1-6 alkyl, halogen, —N(R5)2, —OR5, —CON(R6)2, —SO2N(R6)2,—SO2R5A, or -Q-R5B;
• R3 is optionally substituted C1-9 heteroaryl or optionally substituted C1-9 heteroaryl C1-6 alkyl;
• each R4 is independently hydrogen, halogen, optionally substituted C1-6 alkyl, optionally substituted C2-6 alkenyl, or optionally substituted C2-6 alkynyl;
• each R5 is independently hydrogen, optionally substituted C1-6 alkyl, optionally substituted C6-10 aryl C1-6 alkyl, optionally substituted C6-10 aryl, optionally substituted C1-9 heteroaryl, or —SO2R5A;
• or both R5, together with the atom to which they are attached, combine to form an optionally substituted C2-9 heterocyclyl;
• each R5A is independently optionally substituted C1-6 alkyl, optionally substituted C3-8 cycloalkyl, or optionally substituted C6-10 aryl;
• R5B is hydroxyl, optionally substituted C1-6 alkyl, optionally substituted C6-10 aryl, optionally substituted C1-9 heteroaryl, —N(R5)2, —CON(R6)2, —SO2N(R6)2, —SO2R5A, or optionally substituted alkoxy;
• each R6 is independently hydrogen, optionally substituted C1-6 alkyl, optionally substituted C2-6 alkoxyalkyl, optionally substituted C6-10 aryl C1-6 alkyl, optionally substituted C6-10 aryl, optionally substituted C3-8 cycloalkyl, or optionally substituted C1-9 heteroaryl;
• or both R6, together with the atom to which they are attached, combine to form an optionally substituted C2-9 heterocyclyl;
• Q is optionally substituted C2-9 heterocyclylene, optionally substituted C3-8 cycloalkylene, optionally substituted C1-9 heteroarylene, or optionally substituted C6-10 arylene;
• and
• X is hydrogen or halogen.