Substituent effects in the intramolecular Diels-Alder reaction of 6-furylhexenoates
Substituent effects in the intramolecular Diels-Alder reaction of 6-furylhexenoates
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DOI：
10.1021/jo9721554
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发表时间：
1998-05-01
影响因子：
3.6
通讯作者：
Kiankarimi, M
中科院分区：
文献类型：
--
作者：
Jung, ME;Kiankarimi, M
以呋喃或呋喃为原料，通过直接合成路线合成了系列呋喃烯酮酯4a-c。研究了它们在乙腈和甲苯两种温度下的热分子内Diels-Alder反应生成三环酮5a-c，并测定了反应动力学。将这些数据与相应的酯2得到的内酯3的数据进行比较，表明酯的速率增强(二甲基速率是单甲基的310倍)远远大于酮的速率(二甲基速率是单甲基的6.8倍)。因此，这是对早先的假设的额外证据，即系绳中氧原子的存在是导致比正常速率增加更大的因素。
The series of furyl enone esters, 4a-c, were synthesized from furan or furfural by straightforward routes. Their thermal intramolecular Diels-Alder reactions to give the tricyclic ketones 5a-c were studied in acetonitrile and toluene at two temperatures and the kinetics of the reactions determined. A comparison of these data with that obtained for the corresponding esters 2 to give the lactones 3 indicates that the rate enhancements seen for the esters (rate of dimethyl 310 times that of monomethyl) are much larger than those seen for the ketones (rate of dimethyl 6.8 times that of monomethyl). Thus, this is additional evidence for the earlier hypothesis that the presence of the oxygen atom in the tether is a factor responsible for the larger than normal rate enhancements.