A highly stereocontrolled construction of the C-5-epi ABCDE-ring system of rubriflordilactone B has been developed. The present synthesis features a convergent strategy to construct the C-5-epi AB-ring utilizing Mukaiyama–Michael reaction and forge the CDE ring in one step using intramolecular [2 + 2 + 2] cycloaddition of triynes.