The enantioselective synthesis of simplified southern-half fragments of soraphen A

The compound 2 comprises a southern-half subunit of the fungicidal macrolide soraphen A 1. It was prepared by a Meinwald reaction of the enolate of S-7 with the lactone S-8. Its enantiomer and diastereomers were synthesized in a similar manner. The lactone S-8 and its enantiomer R-8 were prepared by three different routes, including the enantioselective catalytic reduction of the β-keto ester 17. These lactones are new and potentially useful as C-5 asymmetric building blocks.