SYNTHESIS OF BICYCLIC CYCLOPENTANOLS BY PHOTOREDUCTIVE CYCLIZATION OF DELTA,EPSILON-UNSATURATED KETONES
SYNTHESIS OF BICYCLIC CYCLOPENTANOLS BY PHOTOREDUCTIVE CYCLIZATION OF DELTA,EPSILON-UNSATURATED KETONES
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DOI：
10.1021/jo00372a018
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发表时间：
1986-10-31
影响因子：
3.6
通讯作者：
PORTELLA, C
中科院分区：
文献类型：
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作者：
BELOTTI, D;COSSY, J;PORTELLA, C
结果在低压汞灯(=254 nm)下，6，c-烯烃环戊酮1和环己酮3分别高产率地合成了双环环戊醇2和4。对反应混合物的分析表明，除了环化的化合物外，没有发现任何还原化合物，如6，1-烯醇。此外，只得到了一个反式构型中含有甲基和羟基的立体异构体。以三乙胺为供体，在乙腈等极性溶剂中也发生了同样的反应，但产率较低。高的区域和立体选择性以及高产率使我们测试了该反应对各种双环环戊醇的合成用途。以β-烯丙基环己酮(5)为起始原料，分别得到环化异构体6a和6b的混合物，产率分别为45%和30%。未检测到非环化还原产物，1，5环化反应
Results Irradiation of 6, c-olefinic cyclopentanone 1 and cyclohexanone 3 in HMPA with low pressure mercury lamps (= 254 nm) led to the bicyclic cyclopentanols 2 and 4, respectively, in high yields. Analysis of the reaction mixture could not reveal any reduction compound, such as 6,«-olefinic alcohol, otherthan the cyclized one. Furthermore, only one stereoisomer having methyl and hydroxyl groups in trans configuration was obtained. Using triethylamine as donor, in a polar solvent such as aceto-nitrile, the same reaction occurred, butwith poorer yield. The high regio-and stereoselectivity as well as the high yield obtained in HMPA led us to test the synthetic use-fulness of the reaction towardvarious bicyclic cyclo-pentanols. Startingfrom ß-allylcyclohexanone (5), the mixture of cyclized isomers 6a and 6b was obtained, in 45% and 30% yield, respectively. Noncyclized reduction product was not detected and the 1, 5 cyclization process