94 アレニルメチルトリメチルシランを活用する天然物合成(ポスター発表の部)

概要

論文の詳細を見る
For the purpose of exploring a new method to utilize allenylmethyltrimethylsilanes 1 for natural product syntheses, we have undertaken two synthetic studies which are summarized as follows Stereocontrolled syntheses of (-)-kainic acid (11) and (+)-allokainic acid (12), the parent members of the neuroexcitory kainoid amino acids, have been achieved via the common precursor 16 starting with L-serine. The route involves the following major transformations, (i) regioselective addition of iodine to the allenylmethyltrimethylsilane 2(R^1=Me) giving the vic-diiodoallylsilane 3, (ii) N-alkylation of the protected 2-amino-1,3-propanediol 13 derived from L-serine with 3, (iii) diastereoselective radical cyclization leading to the trimethylsilylisopropylidenepyrrolidine 16, and (iv) intramolecular protodesilylation allowing diastereoselective formation of the trisubstituted pyrrolidine (20 or 21) either with the kainic acid stereochemistry or with the allokainic acid stereochemistry. Furthermore, a stereoselective route to the promising synthetic precursor 39 of paeoniflorin (26) has been developed based on a new strategy. The route proceeds through two key steps; Lewis acid mediated addition of the allenylmethyltrimethylsilane 2(R^1=Me) to the ketal 35 giving the diene 36 and intramolecular [2+2] phtocycloaddition of the enone 38 giving 39. The synthesis of paeoniflorin (26) is now in progress.
天然有機化合物討論会の論文
1992-09-10