| Abstract: | A study of the circular dichroism of chlorine-containing guainolides has shown that a negative Cotton effect in the 260-nm region correlates with the trans-linkage of the lactone ring in acroptilin, hyrcanin, chlorohyssopifolin B, elegin, and biebsanin. It has been established that this nature of the linkage does not change on relactonization and hydrogenation. A chloromethylene substituent at C4 causes a bathochromic shift of the lactone Cotton effect.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 650–652, September–October, 1979. |
