Synthesis of central spiro-bis-THF fragments of symbiospirols A–C

Abstract

The gold catalysed alkynediol spiroketalization to assemble the central spiro-bis-THF fragments (C22–C33 and C36–C47) of symbiospirols A–C is documented. The adopted chiral pool approach employed commercially available D-glucose and L-malic acid in the synthesis of key building blocks. In addition, two other possible diastereomers have been synthesized in order to establish the relative stereochemistry of the unassigned THF-center of symbiospirols B/C.