Reduction of Qinghaosu

Wu, Y.-L. Zhang, J.-L., Reduction of qinghaosu with hthium aluminium hydride. Youji Huaxue Chin. J. Org. Chem.), 1986, 6 153-156. 

In 1972, Chinese researchers isolated, by extraction at low temperature from a plant, a crystalline compound that they named qinghaosu [the name artemisinin (la) is preferred by Chemical Abstracts, RN 63968-64-9]. The plant source of artemisinin is a herb, Artemisia annua (Sweet wormwood), and the fact that artemisinin is a stable, easily crystallizable compound renders the extraction and purification processes reasonably straightforward. The key pharmacophore of this natural product is the 1,2,4-trioxane unit (2) and, in particular, the endoperoxide bridge. Reduction of the peroxide bridge to an ether provides an analogue, deoxyartemisinin 3, that is devoid of antimalarial activity. ... 

Study on the reactions of qinghaosu is heuristic, not only for determination of its structure, but also especially for understanding chemical properties and hence for the modification and utilization of the qinghaosu molecule to develop a new medicinal apphcation. Among them, reduction and acidic degradation have been paid the most attention and have received more practical application. 

Qinghaosu can be reduced even more with sodium borohydride in the presence of boron trifluoride to deoxoqinghaosu (100). ° 100 can also be obtained by reduction of 98 with BH3NEt3 and Me3SiCl in DME. ° The more powerful reducing agent lithium aluminium hydride reduces not only lactone and peroxy group, but also acetal and ketal, to yield the exhaustively reduced product 101 and partially reduced products (Scheme 5-3). ° °°... 

Chen, Y. Zhu, S.-M. Chen, H.-Y., Study on the electrochemical behaviors of artemisinin (qinghaosu) and its derivatives n. Reduction mechanism of artemisinin in the presence of hemin. Huaxue Xuebao, 1998, 56 925-929. 

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