Disclosed herein is an isomer, enantiomer, diastereoisomer or tautomer of a compound represented by Formula I: or a prodrug, or a pharmaceutically acceptable salt, or labeled with a detectable label or an affinity tag thereof; wherein R1, R1a, R100, R100a, R2, R200, W, B, and W1 are defined herein. Also disclosed are methods of using compounds of Formula I to treat proliferative disorders such as cancer.