POTENT HYDROPHILIC DIENOPHILES - SYNTHESIS AND AQUEOUS STABILITY OF SEVERAL 4-ARYL AND SULFONATED 4-ARYL-1,2,4-TRIAZOLINE-3,5-DIONES AND THEIR IMMOBILIZATION ON SILICA-GEL
POTENT HYDROPHILIC DIENOPHILES - SYNTHESIS AND AQUEOUS STABILITY OF SEVERAL 4-ARYL AND SULFONATED 4-ARYL-1,2,4-TRIAZOLINE-3,5-DIONES AND THEIR IMMOBILIZATION ON SILICA-GEL
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DOI：
10.1021/jo00164a005
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发表时间：
1983-01-01
影响因子：
3.6
通讯作者：
VANNICE, FL
中科院分区：
文献类型：
--
作者：
KEANA, JFW;GUZIKOWSKI, AP;VANNICE, FL
本研究的目的是开发一系列磺化的4-芳基-1，2，4-三唑啉-3，5-二酮（C3 H4），其可用作水溶液中Diels-Alder反应的有效亲双烯体，并且能够提供固定在不溶性载体上的C3 H4部分。TAD 4、5、23、24和29均通过用N2 O 4氧化相应的尿唑来制备。尿唑前体的制备通过氯磺化适当的4-芳基尿唑，然后在某些情况下，通过水解和中和。虽然二磺酸5和29在分离时不稳定，但23和24中庞大的异丙基的存在使得这些二磺酸可以纯的形式分离，并且在水中足够稳定，以允许Diels-Alder反应成功地与溶剂对二磺酸部分的攻击竞争（参见下文）。尿唑磺酰氯2、18和19与氨丙基硅烷化硅胶31反应，得到相应的固定化磺酰胺，它们容易氧化成黄色硅胶33（红色）和34（紫色）。柠檬酸23和31得到硅胶35，其中柠檬酸部分通过离子键连接到凝胶上。通过这些硅胶从溶液[麦角甾醇与胆固醇或醋酸双烯醇酮的混合物]中选择性地和定量地除去1，3-二烯，并且可以从其中定量地除去。
The purpose of this investigation is the development of a series of sulfonated 4-aryl-1,2,4-triazoline-3,5-diones (TAD) useful as potent dienophiles for Diels-Alder reactions in aqueous solution and capable of providing a TAD moiety immobilized on an insoluble support. TADs 4, 5, 23, 24 and 29 were all prepared by oxidation of the corresponding urazoles with N2O4. The urazole precursors were prepared by chlorosulfonation of the appropriate 4-arylurazole, followed in some cases by hydrolysis and neutralization. While TAD sulfonic acids 5 and 29 were not stable toward isolation, the presence of the bulky isopropyl groups in 23 and 24 rendered these TAD isolable in pure form and sufficiently stable in water to allow Diels-Alder reactions to compete successfully with attack on the TAD moiety by the solvent (see following paper). Urazolesulfonyl chlorides 2, 18 and 19 reacted with aminopropylsilylated silica gel 31 to give the corresponding immobilized sulfonamides, which were readily oxidized to TAD silica gels 33 (red) and 34 (purple). TAD acid 23 and 31 gave silica gel 35 in which the TAD moiety was attached to the gel via an ionic bond. 1,3-Dienes were selectively and quantitatively removed from solution [mixtures of ergosterol with cholesterol or pregnenolone acetate] by these silica gels and could be removed quantitatively therefrom.