A new enantioselective total synthesis of Al-77-B

[GRAPHICS] An enantioselective total synthesis of Al-77-B (1), a gastroprotective subs tance isolated from a culture broth of Bacillus pumilus Al- 77, was perform ed in high overall yield. In this synthesis, the dihydroisocoumarin part 14 and the dihydroxyamino acid part 20 were both assembled from D-ribose as t he common chiral source, For the construction of 14 a bromobenzofuran deriv ative was used as a novel salicylic acid synthon. Finally, DEPC-mediated co ndensation of 14 and 20 yielded Al-77-B (1).