1-(4-Methyoxyphenyl)-2-[[N-(benzyloxycarbonyl)-L-valinyl]amino]-4(S)-hydroxy-5(S)-[[N-(quinolin-2-ylcarbonyl)-L-asparaginyl]amino]-6-phenyl-4-azahexane AIDS-030850 AIDS030850 bis-Val HOEt-N2 aza-peptide isostere