Abstract: Disclosed are chemical entities which are compounds of formula (I): or pharmaceutically acceptable salts thereof; wherein Y, Ra, Ra?, Rb, Rc, X1, X2, X3, Rd, Z1, and Z2 have the values described herein and stereochemical configurations depicted at asterisked positions indicate absolute stereochemistry. Chemical entities according to the disclosure can be useful as inhibitors of Sumo Activating Enzyme (SAE). Further provided are pharmaceutical compositions comprising a compound of the disclosure and methods of using the compositions in the treatment of proliferative, inflammatory, cardiovascular, and neurodegenerative diseases or disorders.