Intramolecular Diels-Alder Cycloaddition Approach toward the cis-Fused Δ5,6-Hexahydroisoindol-1-one Core of Cytochalasins.

Synthesis of the cis-fused Δ5,6-hexahydroisoindol-1-one core of cytochalasins B2-B5, K, Z8, Z9, Z12-Z15, and Z17 has been established starting from an intramolecular Diels-Alder reaction of the amide-tethered (8 E)-1,3,8-nonatriene. The trans-fused 5/6-bicyclic adduct was then subjected to highly stereoselective C9-ß-hydroxylation and epimerization of the C7-α-OH group.

(1S,3aS,4S,7aS)-Ethyl 1-benzyl-2-(4-meth-oxy-benz-yl)-6,7-dimethyl-3-oxo-2,3,3a,4,5,7a-hexa-hydro-1H-isoindole-4-carboxyl-ate dichloro-methane monosolvate.

In the title compound, C(28)H(33)NO(4)·CH(2)Cl(2), the pyrrolidone ring adopts a twisted envelope conformation and the cyclo-hexene has a half-chair conformation. In the crystal, weak C-H⋯O hydrogen bonds link the components into chains along [100].