2005/08/24 by Isamu Shiina, Minako Hashizume, Yu‐suke Yamai +4 · 3 citations
Chemistry · Biochemistry, Genetics and Molecular Biology · #Synthetic Organic Chemistry Methods #Carbohydrate Chemistry and Synthesis #Marine Sponges and Natural Products
paper · doi:10.1002/chem.200500417
openalex publication_date 2005/08/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/26
Octalactin A, an antitumor agent containing an eight-membered lactone moiety, has been stereoselectively prepared by means of enantioselective aldol reactions of selected silyl enolates with achiral aldehydes, promoted by a chiral Sn(II) complex. The medium-sized lactone part was effectively constructed by way of a new and rapid mixed-anhydride lactonization using 2-methyl-6-nitrobenzoic anhydride (MNBA) with a catalytic amount of 4-(dimethylamino)pyridine (DMAP) or 4-(dimethylamino)pyridine 1-oxide (DMAPO). The use of only 5 mol % of DMAP or 2 mol % of DMAPO rapidly promoted formation of the medium-sized ring of the octalactin, demonstrating the remarkable efficiency of the new lactonization protocol.