A compound selected from the group consisting of: and or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: and or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: and or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: and or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: and or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof. selected from the group consisting of: and or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: and or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: and or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: or a pharmaceutically acceptable salt thereof; or selected from the group consisting of: and or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof; or having the structure: or a pharmaceutically acceptable salt thereof.