Efficient total synthesis of AI-77-B, a gastroprotective substance from Bacillus pumilus AI-77

Article abstract of DOI:10.1016/S0040-4020(01)82406-6

First total synthesis of AI-77-B (1), a gastroprotective substance from Bacillus pumilus AI-77, was achieved in a stereoselective and convergent manner. In this synthesis, the dihydroisocoumarin part 2 was constructed in one step through 1,2-addition of the benzylic anion 17b to Boc-L-leucinal 7b. The hydroxy amino acid 4 was elaborated from (R)-glutamic acid in a highly stereoselective manner. Condensation of 2·HCl and 4, intramolecular Pinner reaction, followed by mild hydrolysis afforded AI-77-B (1).