First Chemical Synthesis of the Antiviral Agents S2502 and S2507

Abstract

The first chemical synthesis of S2502 and S2507, highly active antiviral, bioengineered fermentation products, has been achieved using a biomimetic approach. Key steps of the synthesis involved addition of the dianion of acetylacetone to isochromene 10, followed by boron tribromide mediated simultaneous methyl ether cleavage, E/Z isomerization, cyclization, and transesterification/saponification to give S2502 (7) and S2507 (8). In a related reaction, the analogous esters 20 and 21 were obtained by treatment of isochromene 10 with the dianion of methyl acetoacetate, followed by boron tribromide treatment.