Versuche zur enantiomerenreinen Synthese des Chatancins, 1. Mitt. Synthese von (1R,2S,6S,7R,8S,3?S)-2-(4?-Benzyloxy-3?-methylbutoyl)-7-hydroxy-8-isopropyl-1-methylbicyclo [4.4.0]decan-4-on
摘要:
Our first target on the way towards the synthesis of enantiomerically pure chatancin is the preparation of the title compound. The cycloadduct of 5,5-dimethoxy- 1,2,3,4-tetrachlorocyclopentadiene and thymoquinone is stereo- and regioselectively reduced to the tricyclic ketoalcohol 4, which by nucleophilic cyclisation and reductive removal of the keto group as well as the chlorine atoms yielded a tetracyclic dimethoxyketal. Acidic hydrolysis freed the keto group, which now was treated with a chiral lithium alkyl compound derived from methyl (R)-2-methyl-3-hydroxypropionate in few steps. The resulting stereomeric tertiary alkohols were fragmented and the decalinones thus obtained separated. X-ray analysis permitted the determination of the absolute configuration of these decalinone derivatives.
Versuche zur enantiomerenreinen Synthese des Chatancins, 1. Mitt. Synthese von (1R,2S,6S,7R,8S,3?S)-2-(4?-Benzyloxy-3?-methylbutoyl)-7-hydroxy-8-isopropyl-1-methylbicyclo [4.4.0]decan-4-on
作者:W. D. Aichberger、J. Aigner、E. G�ssinger、K. Gruber、G. Menz
DOI:10.1007/bf00812715
日期:——
Our first target on the way towards the synthesis of enantiomerically pure chatancin is the preparation of the title compound. The cycloadduct of 5,5-dimethoxy- 1,2,3,4-tetrachlorocyclopentadiene and thymoquinone is stereo- and regioselectively reduced to the tricyclic ketoalcohol 4, which by nucleophilic cyclisation and reductive removal of the keto group as well as the chlorine atoms yielded a tetracyclic dimethoxyketal. Acidic hydrolysis freed the keto group, which now was treated with a chiral lithium alkyl compound derived from methyl (R)-2-methyl-3-hydroxypropionate in few steps. The resulting stereomeric tertiary alkohols were fragmented and the decalinones thus obtained separated. X-ray analysis permitted the determination of the absolute configuration of these decalinone derivatives.
As an antagonist of the plateletactivatingfactor, chatancin (1), which is isolated from a soft coral, is of potential therapeutic use. The first total synthesis [Eq. (1)] of this structurally unusual diterpene in racemic form is described along with the formal total syntheses of natural (+)-chatancin as well as unnatural (-)-chatancin.