Synthesis of two new chloro derivatives of the guaianolide grossmisin and the crystal structure of one derivative

The reaction of grossmisin (8 alpha -hydroxyachillin, 1) with chlorine in b enzene afforded a mixture of products. The less polar product readily cryst allized after chromatography. According to the X-ray diffraction data, this product has the structure of 1 alpha ,10 beta -dichloro-1,10-dihydrogrossm isin. The second chloro derivative of grossmisin. viz., 8 beta -chloroachil lin. was prepared in good yield by the reaction of lactone 1 with PCl5 in C HCl3 in the presence of Py.