Total synthesis of an enantiomeric pair of FR980482. 2. Syntheses of the aromatic and the optically active aliphatic segments

Article abstract of DOI:10.1016/S0040-4020(97)00651-0

The synthesis of the aromatic segment 4 was achieved starting from commercially available 5-hydroxyisophthalic acid (6) by utilizing Claisen rearrangement of 9, bromolactonization of 12, and modified Curtius rearrangement of 16 as the key steps. Furthermore, the optically active aliphatic segments 5 and ent-5 were synthesized in enantiomerically pure forms starting with natural (2R, 3R)- and unnatural (2S, 3S)-diethyl tartrate (7 and ent-7), respectively: The synthetic scheme features epoxide formation of 26, nucleophilic epoxide opening of 27 with an azide anion, reduction of the azide function in 33 to an amine, and formation of the N-protected 1,3-oxazolidine 35.