Synthesis and chiroptical properties of enantiopure tricyclo[4.3.0.03,8]nonane-4,5-dione (twistbrendanedione)
作者:Eugenius Butkus、Albinas Žilinskas、Sigitas Stončius、Ričardas Rozenbergas、Marie Urbanová、Vladimı́r Setnička、Petr Bouř、Karel Volka
DOI:10.1016/s0957-4166(02)00157-x
日期:2002.4
The synthesis of chiral tricyclo[4.3.0.03,8]nonane-4,5-dione was accomplished starting from enantiomerically pure (+)-(1S,5S)-bicyclo[3.3.1]nonane-2,6-dione 1. Ring contraction of the latter with thallium(III) nitrate proceeded with high stereoselectivity giving exclusively methyl (+)-(1S,4S)-(+)-exo,exo-bicyclo[2.2.1]heptan-2,5-dicarboxylate 2. Inversion of the configuration of this diester to the
手性三环[4.3.0.0 3,8 ]壬烷-4,5-二酮的合成是从对映体纯的(+)-(1 S,5 S)-双环[3.3.1]壬烷-2,6-开始的dione 1。后者与硝酸al(III)的环收缩以高立体选择性进行,仅给出甲基(+)-(1 S,4 S)-(+)- exo,exo-双环[2.2.1]庚烷-2,5-二羧酸2。该二酯的构型转化为所需的二烯通过以下反应序列实现衍生物。相应的酸dichloroanhydride并用乙酸中的锌随后的还原的溴化,得到酯的非对映异构混合物,从该内,内切-酯5经柱色谱法分离。后者与三甲基氯硅烷在甲苯中的缩环蛋白缩合导致分子内闭环,随后烯醇甲硅烷基醚7原位氧化得到三环[4.3.0.0 3,8 ]壬烷-4,5-二酮8。通过电子和振动圆二色性光谱研究了该笼状分子的手性。(1 R,3 R,6R,8 R)标题结构的绝对构型也得到了明确证明。