Disclosed is an isomer, enantiomer, diastereoisomer or tautomer of a compound represented by Formula I or II ##STR00001## or a salt thereof, in which R.sup.1, R.sup.2, R.sup.3, R.sup.100, R.sup.200, R.sup.300, A, A.sup.1, BG, Q and Q.sup.1 are substituents described herein. Also disclosed is the use of compounds of Formula I and II to treat proliferative disorders such as cancer.