Fig. 2

Gram-scale synthesis of (±)-CFA. Five step synthesis of aldehyde 7, followed by syn-selective room temperature aldol addition with ester 8. Aldol addition product 9 undergoes dehydration and IMDA cyclization of the resultant triene at elevated temperature. DHP: dihydropyran, DMSO: dimethyl sulfoxide, PPTS: pyridinium p-toluenesulfonate, DIPEA: N,N-diisopropylethylamine, DIC: N,N’-diisopropylcarbodiimide, PTSA: p-toluenesulfonic acid, PDC: pyridinium dichromate