Fused tricyclic ether carbamates and their use

A compound of the formula

• or a pharmaceutically acceptable salt thereof, wherein
• X1 is a bond or optionally substituted alkylene;
• X2 is a bond, C(O), S(O), S(O)2, optionally substituted amino, or optionally substituted alkylene;
• R1 and R2 are in each instance independently selected from the group consisting of hydrogen, P(O)(OR)2, and a prodrug forming group, where R is independently selected in each instance from hydrogen or alkyl;
• R3 is sulfonyl, acyl, amino, alkyl, heteroalkyl, cycloalkyl, cycloheteroalkyl, aryl, arylalkyl, heteroaryl, or heteroarylalkyl, each of which is optionally substituted;
• R4 is hydrogen, halogen, —OH, or —NO2, or R4 is amino, alkoxyl, sulfonyl, acyl, alkyl, heteroalkyl, cycloalkyl, cycloheteroalkyl, aryl, and heteroaryl, each of which is optionally substituted;
• or R3, R4, X2 and the attached nitrogen form an optionally substituted heterocyclyl;
• R5 and R6 are independently in each instance hydrogen or selected from the group consisting of alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, arylalkyl, heteroaryl, and heteroarylalkyl, each of which is optionally substituted;
• Z is
• wherein * indicates the point of attachment;
• m is 0, 1, or 2;
• W1 and W2 are in each instance independently selected from the group consisting of optionally substituted alkylene, alkyleneoxy, alkyleneamino, alkylenethio, alkylenesulfoxyl, and alkylenesulfonyl;
• W3 and W4 are in each instance independently selected from the group consisting of amino, oxygen, alkylene, alkyleneoxy, alkyleneamino, and heteroalkylene, wherein at least one of W1 or W2 is oxygen, and wherein when one of W1 or W2 is optionally substituted methylene, at least one of W3 or W4 is oxygen or alkyleneoxy, and wherein Z does not include a peroxide bond, a sulfenate bond, or a sulfenamide bond;
• X3 is a bond or optionally substituted methylene;
• and
• Y is hydrogen, hydroxyl, or carbonyl, or amino, acyl, sulfonyl, alkyl, or heteroalkyl, each of which is optionally substituted is described;
• or
• Z is
• wherein * indicates the point of attachment;
• n is 1, 2, or 3;
• W1 and W2 are in each instance independently selected from the group consisting of optionally substituted methylene, oxygen, and amino;
• W3 and W4 are in each instance independently selected from the group consisting of amino, oxygen, alkylene, and heteroalkylene, wherein at least one of W1 or W2 is oxygen, and wherein when one of W1 or W2 is optionally substituted methylene, at least one of W3 or W4 is oxygen, and wherein Z does not include a peroxide bond, a sulfenate bond, or a sulfenamide bond;
• X3 is a bond or optionally substituted methylene;
• and
• Y is hydrogen, hydroxyl, or carbonyl, or amino, acyl, sulfonyl, alkyl, or heteroalkyl, each of which is optionally substituted.