C–S bond cleavage in the sensitized photooxygenation of tert-alkyl phenyl sulfides. The role of superoxide anion
作者:Enrico Baciocchi、Tiziana Del Giacco、Paolo Giombolini、Osvaldo Lanzalunga
DOI:10.1016/j.tet.2005.09.154
日期:2006.7
presence of oxygen mostly derive from the decomposition of a thiadioxirane 6 formed by the reaction of the sulfide radical cation with O2−. In this cleavage a sulfinate and a carbocation formed. The former is oxidized to sulfonate, whereas the carbocation can react with adventitious water to form the alcohol (and the alkene therefrom) and with O2− to produce the ketone. For 2 (a sulfide with α-CH bonds) probably
所述Ñ -methylquinolinium四氟硼酸盐(NMQ +)的氧化-photosensitized叔-烷基苯基硫化物1A - Ç(1A,叔-烷基=叔丁基; 1b中,叔烷基= 2-苯基-2-丙基; 1C,叔-在CH 3 CN中,通过纳秒激光闪光光解(LFP)和在氮或O 2存在下的稳态辐射,研究了在CH 3 CN中的烷基= 1,1-二苯基乙基)和苄基苯基硫醚(2)。通过激光照射,形成硫化物自由基阳离子1A + - Ç +在单体形式(λ最大= 520纳米)和2 +在两个单体(λ最大= 520纳米)和二聚体形式(λ最大观察到的激光脉冲内= 780纳米)。在这两种情况下,自由基阳离子都通过二阶动力学衰减,而没有任何明显的由C–S键断裂引起的瞬态形成。与这些结果一致,在氮下获得了非常少量的光产物,因此表明硫化物自由基阳离子主要经历带有还原的N-甲基喹啉鎓(NMQ)的反向电子转移过程。)。与LFP实验相反,在O