A SYNTHETIC STUDY FOR OPTICALLY ACTIVE 2H-CHROMENE TRIMERS

天然芋螺香酮是一种具有光学活性的吡喃萘醌三聚体，有效合成芋螺香酮的步骤包括：有效制备关键化合物吡喃四氢萘酮，将吡喃四氢萘酮分别转化为相应的氢化萘醌和萘醌，然后将两种单体萘醌、两摩尔羟基萘醌和一摩尔萘醌三聚。在第一年，2 H-色烯-6-丁酸的分子内环化，通过一些2 H-色烯与琥珀酸氢甲酯酰化，然后还原和水解制备，被发现是不是有效的关键吡喃四氢萘酮的制备。在第二年，7-羟基-1-四氢萘酮的炔丙基醚的热环化被发现是最有效的关键化合物。通过炔丙基醚的区域选择性热环化反应，合成了具有萘并[2，1-B]吡喃结构的四氢萘酮。但是，由于炔丙基醚化反应中的外消旋化，类似的具有异戊烯基侧链的手性吡喃四氢萘酮的制备失败，因此热环化得到外消旋吡喃四氢萘酮。具有异戊烯基侧链的吡喃四氢萘酮及其二甲基类似物分别转化为相应的羟基萘醌和萘醌。由此获得的具有异戊二烯基侧链的羟基萘醌和萘醌与天然的Teretifolone B及其脱氧衍生物相同。2摩尔的二甲基羟基萘醌和1摩尔的二甲基萘醌的三聚得到芋螺酮的二甲基类似物。核磁共振氢谱表明存在阻转异构现象，二甲基类似物三聚体的结构研究和手性吡喃四氢萘酮的制备尚待进一步研究。

Natural conocurvone is an optically active pyranonaphthoquinone trimer, and the effective synthesis of conocurvone, consist of the effective preparation of a pyranotetralone as the key compond, the respective conversions of the pyranotetralone to the corresponding hydronaphthoquinone and naphthoquinone, and followed by trimerization of both monomeric naphthoquinones, two moles of the hydroxynaphthoquinone and one mole of the naphthoquinone. In the first year, the intramolecular cyclization of 2H-chromene-6-butanoic acids, prepared by acylation of some 2H-chromene with methyl hydrogensuccinate followed by reduction and hydrolysis, was found not to be effective for the preparation of the key pyranotetralone. In the second year, the thermal cyclization of the propargyl ether of 7-hydroxy-1-tetralone was found to be most effective for the key compound. Some tetralones having a naphtho[2, 1-b] pyran structure, were preprared by the regioselective thermal cyclization of the corresponding propargyl ethers. But, a similar preparation of the chiral pyranotetralone, having the prenyl side-chain was falied, because of racemization in the the propargyl etherification, and so the thermal cyclization gave the racemic pyranotetralone. The pyranotetralone, having a prenyl side-chain, and its dimethyl analog were converted respectively to the corresponding hydroxynaphthoquinones and naphthoquinones. Thus obtained hydroxyraphthoquinone and naphthoquinone, having the prenyl side-chain, thus prepared were identical with natural teretifolione B and its deoxy derivative. Trimerization of two mole of dimethylhydroxynaphthoquinone and one mole of dimethylnaphthoquinone gave the dimethyl analog of conocurvone. The ^1H NMR showed the existence of atrop isomerism.The structural investigation for the dimethylanalogous trimer and the preparation of the chiral pyranotetralone are left to study.