Two novel 1,2,4,5-tetrazines that participate in inverse electron demand Diels-Alder reactions with an unexpected regioselectivity
Two novel 1,2,4,5-tetrazines that participate in inverse electron demand Diels-Alder reactions with an unexpected regioselectivity
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DOI：
10.1021/jo051832o
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发表时间：
2006-01-06
影响因子：
3.6
通讯作者：
Boger, DL
中科院分区：
文献类型：
--
作者：
Hamasaki, A;Ducray, R;Boger, DL
合成了两种新的不对称1，2，4，5-四嗪化合物：3-甲基亚磺酰基-6-甲硫基-1，2，4，5-四嗪（4）和3-苄氧羰基氨基-6-甲基亚磺酰基-1，2，4，5-四嗪（5），并确定了它们参与分子间逆电子需求Diels-Alder反应的范围。如所预期的，亚砜4和5（4 > 5）显示出显著大于其相应硫化物（2和3）的反应性，这源自其增强的缺电子特性并且导致更宽范围的潜在亲二烯体选择或使用更温和的反应条件。环加成反应是非区域选择性的，通常产生单个环加合物，确保其合成效用，但发现两者都以与预期相反的区域选择性进行，并且与2和3观察到的区域选择性互补。
Two new unsymmetrical 1,2,4,5-tetrazines, 3-methylsulfinyl-6-methylthio-1,2,4,5-tetrazine (4) and 3-(benzyloxycarbonyl)amino-6-methylsulfinyl-1,2,4,5-tetrazine (5), were prepared, and the scope of their participation in intermolecular inverse electron demand Diels-Alder reactions was defined. As anticipated, sulfoxides 4 and 5 (4 > 5) display a reactivity that is substantially greater than that of their corresponding sulfides (2 and 3), being derived from their enhanced electron-deficient character and resulting in a wider range of potential dienophile choices or the use of milder reaction conditions. The cycloaddition reactions were expectedly regioselective, typically producing a single cycloadduct, ensuring their synthetic utility, but both were found to proceed with a regio selectivity opposite what would be anticipated and complementary to that observed with 2 and 3.