2-Imidazolyl OHEt isostere 2-[(1R,3S,4S)-1-Benzyl-4-[[N-(benzyloxycarbonyl)-L-valyl]amino]-3-hydroxy-5-phenylpentyl]-4(5)-(2,2-dimethyl-1-oxo-3-butenyl)imidazole AIDS-044549 AIDS044549