2-Methyl-2-[[N-(benzyloxycarbonyl)-L-valinyl]amino]-6(S)-hydroxy-7(S)-[[N-(quinolin-2-ylcarbonyl)-L-asparaginyl]amino]-8-phenyl-4-azaoctane AIDS-030843 AIDS030843 bis-Val HOEt-N2 aza-peptide isostere