Patent ID: 6884869

Claim:
A compound of the formula and pharmaceutically acceptable salts and solvates thereof wherein, independently at each location: R 2 is selected from hydrogen and lower alkyl; R 3 is lower alkyl; R 4 is selected from lower alkyl, aryl, and —CH 2 —C 5-7 carbocycle when R 5 is selected from H and methyl, or R 4 and R 5 together form a carbocycle of the partial formula —(CR a R b ) n — wherein R a and R b are independently selected from hydrogen and lower alkyl and n is selected from 2, 3, 4, 5 and 6; R 6 is selected from hydrogen and lower alkyl; R 7 is sec-butyl or iso-butyl; R 8 is selected from hydrogen and lower alkyl; R 11 is selected from hydrogen and lower alkyl; and R 18 is selected from hydrogen, a hydroxyl protecting group, and a direct bond where OR 18 represents ═O.