The caryophyllene derivative lychnophoric acid (2) and several eremantholides have been isolated from the cytotoxic extracts of L. affinis as well as two germacranolides, lychnophorolides A and B, having both «-methylene 7-lactone and 3(2fl)-furanone electrophilic functions. The structure of lychnophorolide A has been shown to be 3 by X-ray analysis, and lychnophorolide B is assigned structure 4. Comparison of bond lengths and angles from the crystal structure determination of lychnophorolide A and the previously determined eremantholides A and B shows a remarkable conformational similarity in the cyclodecadienone rings of these compounds.

3), ZHC2H, 116.4 (1)°, and (assuming a symmetrical HC2H groups), C3-, 1.081 (1) A and zCiC3H, 120.5 (2)°,22 The F1C2H plane is displaced from the SC2Ci angle bisector plane by an angle of 7.2°b ringing these hydrogens closer to the S atom. The dipole moment of 3 is 1.36 (2) D.The mechanism proposed in eq 2 to account for the scrambling of 13C and deuterium labeling in 3 is consistent with the long, and presumably weakened, C2-S bond in 3.23•24 Aliene episulfide has a gas-phase lifetime varying from ~3 min (room temperature) to ~20 min (dry ice temperature) at ~0.05 Torr and may be revolatilized after condensation at -196 °C. Efforts are currently underway to define more precisely the equilibrium of eq 1 by experimental as well as theoretical methods and to synthesize cyclopropanethiones by nonpyrolytic routes.26

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