The crystal structure of gliotoxin

Gliotoxin, C13H1404N2S2, a fungal product from Gliocladium fimbriatum, crystallizes in the monoclinic system with a= 10.17, b= 7.49, c= 18-28 A,, fl= 100.7 ° (at 150°C), Z=4. The space group being P2x, there are two independent molecules in the asymmetric unit. The structure was determined with data (2856 reflexions) from Weissenberg photographs of 6 layers around the b axis and 7 layers around the a axis by means of a three-dimensional Patterson distribution and a Fourier synthesis, and refined by full-matrix least-squares calculations and difference syntheses to R--0.088. The skeletal structure consists of a disulphide-bridged piperazinedione system linked through a five-membered pyrrolidinetype ring to a cyclohexadiene ring and three side groups of-CH3, -CHEOH and -OH. The absolute configuration has been determined by the use of the anomalous dispersion of the sulphur atoms, establishing the chirality of the skew diene chromophore and of the disulphide bridge.