Cytochalasan synthesis: macrocycle synthesis using intramolecular Diels–Alder reactions. X-Ray crystal structure of 10-phenyl[11]cytochalasa-6(7),13t-diene-1,21-dione

Abstract

An approach to the total synthesis of cytochalasans has been developed which makes use of an intramolecular Diels–Alder reaction to close the large ring simultaneously forming the hydrogenated isoindolone unit with the desired stereochemistry. Conjugated trienes were found to be more efficient than dienes as the diene components for these reactions. Thus the long chain 3-(1-oxotrienyl)pyrrol-2(5H)-one (36) gave a useful yield of the [11]cytochalasan (37) when heated in toluene at 100 °C. The structure of 10-phenyl[11]cytochalasa-6(7),13^t-diene-1,21-dione (38) was established by X-ray crystallography.