When Ethyl Is Infinitely Different from Methyl: Double Addition of Lithiated Dithianes to Aromatic Carboxylates Revisited
作者:Roman A. Valiulin、Rudresha Kottani、Andrei G. Kutateladze
DOI:10.1021/jo060780f
日期:2006.6.1
benzoate does not produce the expected product of double addition, α,α-bis(alkyldithianyl) benzyl alcohol, for alkyls larger than methyl. Instead, the first step intermediate, i.e. 2-benzoylated dithiane, undergoes an electron-transfer reduction by the second molecule of the dithianyl anion. This reduction is followed by the ring-opening mesolytic fragmentation of the dithiane ring in the ketyl anion radical
对于大于甲基的烷基,将锂化的烷基二噻烷添加到苯甲酰氯或苯甲酸甲酯中不能产生预期的双重添加产物,即α,α-双(烷基二噻吩基)苄醇。相反,第一步中间体,即2-苯甲酰化的二噻吩,通过二噻吩基阴离子的第二分子而经历电子转移还原。该还原之后是酮基阴离子自由基中二噻吩环的开环介观断裂,随后进行自由基重组,生成苯乙酮系的硫代原酸酯4,α-[3-(2-烷基-1,3-二硫代烷-2-)乙硫基丙硫基]-α-烷基苯乙酮。看来,锂化二噻吩的Corey-Seebach双加成反应成苯甲酸甲酯是一个例外,而不是烷基二噻吩系列中的规则。