On Helenine from Sre?ko Bo?njakovi? to Lavoslav Ru?i?ka – Model Example for Development of Organic Chemistry in 20th Century

摘要

Prof. Sre?ko Bo?njakovi? (1865?–?1907) is considered as the first Croatian chemist who completed Ph. D. thesis in the field of organic chemistry. In his thesis published in 1893 under the title “Gerhardt’s Helenine” S. Bo?njakovi? has described isolation of helenine from the roots of Inula helenium L., separation of chemically pure substances and determination of their empirical formulae by elemental analysis. In his thesis the names helenine and alantolactone were used, the second one appears exclusively in the recent literature. Since this name indicates existence of lactone group in helenine it was interesting to investigate what was known at that time about the structure of this natural product, in particular who has determined exact structure of alantolactone and its isomers and congeners, sesquiterpenes present in the Nature. It turned out that our Nobel laureate Lavoslav Ru?i?ka greatly contributed to the knowledge of this field, who in the period 1931?–?1936 investigated structures of numerous sesquiterpenes and formulated well-known Ru?i?ka’s biogenetic isoprene rule (L. Ru?i?ka, The isoprene rule and the biogenesis of terpenic compounds, Experientia 9 (1953) 357–396).Prompted by this unexpected “Croatian connection by helenine”, I have discovered interesting development of chemistry related to alantolactone, in particular contribution of Lavoslav Ru?i?ka to structure determination.In this review the work of Bo?njakovi? and Ru?i?ka is presented and new results revealed on structure determination, synthesis and important biological properties of alantolactone and related sesquiterpenes. Most recent results and accumulated knowledge on alantolactone represent an excellent example for development of organic chemistry in the XXth century.