Photochemical ?-Cleavage of ?, ?-Unsaturated Aryl Ketones: Competition between recombination/disproportionation and dissociation in geminate singlet and triplet radical pairs
作者:Hans-Ulrich Gonzenbach、Kurt Schaffner、Bernd Blank、Hanns Fischer
DOI:10.1002/hlca.19730560534
日期:1973.7.18
the triplet state; (2): that recombination and disproportionation reactions within the geminate singlet and triplet aroyl/allyl radical pairs (11) compete with the dissociation into free radicals (12): (3): that ketone isomerization by paths not involving polarizable radical intermediates is unimportant; (4): that no triplet oxa-di-π-methane type rearrangement products are formed.
(+) - - (R)的光解苯基和(R) - (+) - p -anisyl 1,2,3三甲基丙-2-烯基酮(1,2)和相应的外消旋-1-和3脱甲基类似物(3,4)导致异构化由于正式1,3芳酰基迁移并形成芳基醛类(的7,8),二烯(9,10)和二聚体(5,6的环戊烯基的基团)。从交叉实验的质谱分析和光解CIDNP测量(包括使用CCl 4)获得的证据作为自由基清除剂,支持以下结论(1):酮主要以三重态进行光化学α裂解;(2):使成双的单线态和三芳酰基/烯丙基双(内重组和歧化反应11)与离解成自由基(竞争12):(3):由不涉及极化自由基中间体路径那酮异构化是不重要; (4):未形成三重态氧杂-二-π-甲烷型重排产物。