Total synthesis of (RS)- and (R)-3-alkanoyl-5-hydroxymethyltetronic acid homologues, HIV-1 protease inhibitory natural products

5-Acetoxymethyl-gamma-butyrolactone-3-carboxylic acids [(RS)-4a and (S)-4a] were prepared as racemic form starting from dibenzyl allylmalonate (5b) an d optically active S form starting from (4S)-4-[2,2-bis(benzyloxycarbonyl)e thyl]-2,2-dimethyl-1,3-dioxolane [(S)-6b], and the 3-position of (RS)-4a an d (S)-4a was acylated to afford (RS)-3a, (S)-3a, and(S)-3b. Phenylselenenyl ation of (RS)-3a, (S)-3a, and (S)-3b followed by H2O2-oxidation and subsequ ent acidic hydrolysis afforded the HIV-1 protease inhibitory 3-alkanoyl-5-h ydroxymethyltetronic acids [(RS)-1a, (R)-1a, and (R)-1d, respectively].