14-Noreudesma-4,11-dien-3,9-diones′ analogues were treated with DDQ in dioxane and afforded the rearranged aromatic products. The similar compounds to eudesma-4,11-dien-3,9-diones had no reaction. 9-Actoxy-14-noreudesma-4,11-dien-3-ones, 9-actoxy-eudesma-4,11-dien-3-ones and their analogues yielded the normal 1,2-dehydro-products. The mechanism of the rearrangement was discussed.
In the sesquiterpenic family, β-dihydroagarofuran and a large number of eudesmanes have an oxygenated func tional group at C1. [1] Although considerable efforts have been devoted to the total synthesis of eudesmane β-dihydroagarofuran and some germacrane sesquiterpenoids starting from the corresponding eudesmane over the pastdecades, the introduction of C1 oxygenated functional group still represents significant challenge.……
CHEN Jin-Chun ZHENG Guo-Jun FANG Li-Jing LI Yu-Lin
Baker抯 yeast mediated reduction of optically active diketone is described. The two keto groups are efficiently dif-ferentiated and the ee value of the recovered material is considerably raised. It affords highly optically active key intermediates efficiently for the synthesis of natural polyhydroxylated agarofuran products.
An enhancive synthesis of (±)-1β, ll-dioi-4-en-eudesmoi,starting from 2-chloroacrylonitrile, is described. The effect of temperature on the Diels-Aider reaction of 2-chloroacryionitrile with 2-methylfuran and the condition of cationic cyclization of diene were discussed in detail.
Dehydrogenation of 9-hydroxy decalinic enones and analogs with DDQ resulted in a formal dienone-phenol type rearrangement via B-ring cleavage, while the corresponding dienone acetates underwent base-catalyzed formal dienone-phenol type rearrangement analogously.
Jing Chun CHEN, Gang ZHOU, Wei Dong LI*, Yu Lin LI* National Laboratory of Applied Organic Chemistry and Institute of Organic Chemistry, Lanzhou University, Lanzhou 730000
3-Oxo-11,12,13-trihydroxyeudesm-4-ene(1) was a highly oxygenated natural eudesmane isolated from traditional herbal medicine with an antiphlogostic and spasmolytic activity.For the purpose of pharmacological activity research on natural product 1 and its derivatives,a facile total synthesis of compound 1 starting from(+)-dihydrocarvone(2) was completed in an overall yield of 24%.The structures of all intermediates and product 1 were confirmed via 1H NMR,13C NMR,MS and IR techniques.The NMR data of compound 1 are in agreement with those of natural products.
