Summary The synthesis of (3 R, 3'S, 5'R)-capsanthin (l),(3 S, 5 R, 3'S, 5'R)-capsorubin (2), and (3'S, 5'R)-cryptocapsin (3), found in the red paprika Capsicum annuum, is described using (+)-camphor (7) as a readily available starting material. As the key reaction, the unsaturated acetal 16 is hydroborated with (+)-diisopinocampheylborane to give the hydroxy ketone 12a in very high chemical and optical yield. A subsequent aldol condensation with ...
