Hsp90b n-terminal isoform-selective inhibitors

A compound according to Formula I

• or a pharmaceutically acceptable salt and/or solvate thereof, wherein
• X1, X2, X3, and X4 are each independently selected from H, F, Cl, Br, I, sulfoxide, sulfone, nitro, pentafluorosulfanyl, C(O)OH, amide, or ester;
• R1 is OH, C1-C3 alkyl, C2-C4 alkenyl, or —CH2OH;
• R2 is CH2—X5 or OH, where X5 is OH, F, Cl, Br, CN, —C(O)—NR4R5, —NR6—C(O)H, —NR7—C(O)-alkyl, C(O)H, C(O)OH, sulfonamido, sulfoxide, sulfone, or S(O)2OH;
• or R1 and R2 together are (moving in the direction from R2 to R1) —C(X6)—CH2—, —C(X7)—CH(R8)—CH(R9)—, —C(X8)—N(R10)—CH(R11)—, —C(X9)—CH(R12)—CH(R13)—CH(R14)—, —C(X10)—N(R15)—CH(R16)—CH(R17)—, —O—CH═CH—, —O—N═CH—, —NH—CH═N—, or —CH═N—NH—;
• X6, X7, X8, X9, and X10 are each independently selected from O, CH2, and CF2;
• R3 is alkyl, —CH(CH3)2, CF3, Br, sulfonamido, sulfoxide, sulfone, nitro, pentafluorosulfanyl, C(O)OH, amide, or ester;
• R4, R5, R6, and R7 are each independently H or alkyl;
• R8, R9, R11, R12, R13, R14, R16, and R17 are each independently selected from H, C1-C3 alkyl, F, Cl, Br, I, or CF3;
• and
• R10 and R15 are each independently H or C1-C3 alkyl.