antiproliferative natural products cortistatins A (1) and J (5) in their naturally occurring enantiomeric forms are described. The modular and convergent strategy employed relies on an intramolecular oxa-Michael addition/aldol/dehydration cascade reaction to cast the ABCDring framework of the molecule and both Sonogashira and Suzuki-Miyaura coupling reactions to assemble the necessary building blocks into the