Disclosed are compounds of formula (I); or a pharmaceutically acceptable salt thereof; wherein Y, Ra, Ra′, Rc, Rf, X2, Rd, Rd′, Re, Re′, m, and G have the values described herein and stereochemical configurations depicted at asterisked positions indicate absolute stereochemistry, 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.