Substituted pyrazino[1′,2′:1 ,5]pyrrolo[2,3-b]-indole-1,4-diones for cancer treatment

1. A compound having the structure of formula I-a:

or a pharmaceutically acceptable salt thereof, wherein:

is a single bond or a double bond, as valency permits;

R 1 is R, —C(O)R, —C(O)N(R) 2 —S(O)R, —S(O) 2 R, —S(O) 2 OR, —C(R) 2 OR, or —S(O) 2 N(R) 2 ;

each R is independently hydrogen or a group selected from C 1-20 aliphatic, C 1-20 heteroalkyl, phenyl, a 3-7 membered saturated or partially unsaturated carbocyclic ring, an 8-14 membered bicyclic or polycyclic saturated, partially unsaturated or aryl ring, a 5-6 membered mono cyclic heteroaryl ring having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, a 3-7 membered saturated or partially unsaturated heterocyclic ring having 1-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur, a 7-14 membered bicyclic or polycyclic saturated or partially unsaturated heterocyclic ring having 1-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an 8-14 membered bicyclic or polycyclic heteroaryl ring having 1-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur; or:

two R groups are optionally taken together with their intervening atoms to form a 3-14 membered, saturated, partially unsaturated, or aryl ring having, in addition to the intervening atoms, 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur;

R 2 is hydrogen, —[C(R) 2 ] q —OR, —[C(R) 2 ] q —N(R) 2 , —[C(R) 2 ] q —SR, —[C(R) 2 ] q —OSi(R) 3 , —[C(R) 2 ] q —OC(O)R, —[C(R) 2 ] q —OC(O)OR, —[C(R) 2 ] q —OC(O)N(R) 2 , —[C(R) 2 ] q —OC(O)N(R)—SO 2 R or —[C(R) 2 ] q —OP(OR) 2 ;

each q is independently 0, 1, 2, 3, or 4;

R 3 is —SO 2 R or —COCF 3 ;

R 4 is absent when is a double bond or is R or halogen;

R 5 is absent when is a double bond or is hydrogen or a C 1-6 aliphatic group;

each of R 6 and R 6′ is independently R, halogen, —CN, —NO 2 , —OR, —SR, —N(R) 2 , —S(O) 2 R, —S(O) 2 N(R) 2 , —S(O)R, —C(O)R, —C(O)OR, —C(O)N(R) 2 , —C(O)N(R)—OR, —N(R)C(O)OR, —N(R)C(O)N(R) 2 , —N(R)S(O) 2 R, or —OSi(R) 3 ; or

R 6 and R 6′ are taken together to form ═O, ═C(R) 2 or ═NR;

n is 0, 1, 2, 3, or 4;

each R 7 is independently R, halogen, —CN, —NO 2 , —OR, —OSi(R) 3 , —SR, —N(R) 2 , —S(O) 2 R, —S(O) 2 OR, —S(O) 2 N(R) 2 , —S(O)R, —C(O)R, —C(O)OR, —C(O)N(R) 2 , —C(O)N(R)—OR, —N(R)C(O)OR, —N(R)C(O)N(R) 2 , —N(R)S(O) 2 R, —P(R) 2 , —P(OR) 2 , —P(O)(R) 2 , —P(O)(OR) 2 , —P(O)[N(R) 2 ] 2 —B(R) 2 , —B(OR) 2 , or —Si(R) 3 ;

R 8 is —(S) m —R x wherein m is 1, 2, or 3, and R x is R, —SR, —C(O)R, —C(O)OR, —C(O)N(R) 2 , —C(S)R, —S(O)R, —S(O) 2 R, or —S(O) 2 N(R) 2 ; and

R 9 is —(S) p —R y wherein p is 1, 2, or 3, such that the sum of m and p is 2, 3, or 4, and R y is R, —SR, —C(O)R, —C(O)OR, —C(O)N(R) 2 , —C(S)R, —S(O)R, —S(O) 2 R, or —S(O) 2 N(R) 2 ; or

R 8 and R 9 are taken together to form —S—, —(S) m —[C(R) 2 ] q —(S) p —, —(S) m —(S) p —, —(S) m —C(O)—(S) p —, —(S) m —C(S)—(S) p —, —(S) m —S(O)—(S) p —, or —(S) m —S(O) 2 —(S) p —.

2. The compound of claim 1 , wherein R 3 is —SO 2 Ph.

3. The compound of claim 2 , wherein R 8 and R 9 are taken together to form —S—, —(S) m —(CH 2 )—(S) p —, —(S) m —(S) p —, —(S) m —C(O)—(S) p —, or —(S) m —C(S)—(S) p —.

4. The compound of claim 3 , wherein each of R 5 , R 6 and R 6′ is independently hydrogen.

5. The compound of claim 4 , wherein R 8 and R 9 are taken together to form —S—S—.

6. A compound having the structure of formula I-b:

or a pharmaceutically acceptable salt thereof, wherein:

each R 1 is independently R, —C(O)R, —C(O)N(R) 2 , —S(O)R, —S(O) 2 R, —S(O) 2 OR, —C(R) 2 OR, or —S(O) 2 N(R) 2 ;

each R is independently hydrogen or a group selected from C 1-20 aliphatic, C 1-20 heteroalkyl, phenyl, a 3-7 membered saturated or partially unsaturated carbocyclic ring, an 8-14 membered bicyclic or polycyclic saturated, partially unsaturated or aryl ring, a 5-6 membered monocyclic heteroaryl ring having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, a 3-7 membered saturated or partially unsaturated heterocyclic ring having 1-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur, a 7-14 membered bicyclic or polycyclic saturated or partially unsaturated heterocyclic ring having 1-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an 8-14 membered bicyclic or polycyclic heteroaryl ring having 1-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur; or:

two R groups are optionally taken together with their intervening atoms to form a 3-14 membered, saturated, partially unsaturated, or aryl ring having, in addition to the intervening atoms, 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur;

each R 2 is independently R, —[C(R) 2 ] q —OR, —[C(R) 2 ] q —N(R) 2 , —[C(R) 2 ] q —SR, —[C(R) 2 ] q —OSi(R) 3 , —[C(R) 2 ] q —OC(O)R, —[C(R) 2 ] q —OC(O)OR, —[C(R) 2 ] q —OC(O)N(R) 2 , —[C(R) 2 ] q —OC(O)N(R)—SO 2 R or —[C(R) 2 ] q —OP(OR) 2 ;

each q is independently 0, 1, 2, 3, or 4;

each R 3 is —SO 2 R;

each R 5 is independently hydrogen or a C 1-6 aliphatic group;

each of R 6 and R 6′ is independently R, halogen, —CN, —NO 2 , —OR, —SR, —N(R) 2 , —S(O) 2 R, —S(O) 2 N(R) 2 , —S(O)R, —C(O)R, —C(O)OR, —C(O)N(R) 2 , —C(O)N(R)—OR, —N(R)C(O)OR, —N(R)C(O)N(R) 2 , —N(R)S(O) 2 R, or —OSi(R) 3 ; or

R 6 and R 6′ are taken together to form ═O, ═C(R) 2 or ═NR;

each n is independently 0, 1, 2, 3, or 4;

each R 7 is independently R, halogen, —CN, —NO 2 , —OR, —OSi(R) 3 , —SR, —N(R) 2 , —S(O) 2 R, —S(O) 2 OR, —S(O) 2 N(R) 2 , —S(O)R, —C(O)R, —C(O)OR, —C(O)N(R) 2 , —C(O)N(R)—OR, —N(R)C(O)OR, —N(R)C(O)N(R) 2 , —N(R)S(O) 2 R, —P(R) 2 , —P(OR) 2 , —P(O)(R) 2 , —P(O)(OR) 2 , —P(O)[N(R) 2 ] 2 , —B(R) 2 , —B(OR) 2 , or —Si(R) 3 ;

each R 8 is independently —(S) p —R x wherein m is 1, 2, or 3, and R x is R, —SR, —C(O)R, —C(O)OR, —C(O)N(R) 2 , —C(S)R, —S(O)R, —S(O) 2 R, or —S(O) 2 N(R) 2 ; and

each R 9 is independently —(S) p —R y wherein p is 1, 2, or 3, such that the sum of m and p is 2, 3, or 4, and R y is R, —SR, —C(O)R, —C(O)OR, —C(O)N(R) 2 , —C(S)R, —S(O)R, —S(O) 2 R, or —S(O) 2 N(R) 2 ; or

R 8 and R 9 are taken together to form —S—, —(S) m —[C(R) 2 ] q —(S) p —, —(S) m —(S) p —, —(S) m —C(O)—(S) p —, —(S) m —C(S)—(S) p —, —(S) m —S(O)—(S) p —, or —(S) m —S(O) 2 —(S) p —.

7. The compound of claim 6 , wherein R 3 is —SO 2 Ph.

8. The compound of claim 7 , wherein R 8 and R 9 are taken together to form —S—, —(S) m —(CH 2 )—(S) p —, —(S) m —(S) p —, —(S) m —C(O)—(S) p —, or —(S) m —C(S)—(S) p —.

9. The compound of claim 8 , wherein each of R 5 , R 6 and R 6′ is independently hydrogen.

10. The compound of claim 9 , wherein R 8 and R 9 are taken together to form —S—S—.

11. A compound selected from the group consisting of: