Photo-Arbuzov Rearrangements of 1-Arylethyl Phosphites: Stereochemical Studies and the Question of Radical-Pair Intermediates
作者:Worawan Bhanthumnavin、Wesley G. Bentrude
DOI:10.1021/jo001545e
日期:2001.2.1
The direct UV irradiation of the 1-arylethyl phosphites 7, 8, and 9 was carried out in acetonitrile, benzene, and cyclohexane, as was the triphenylene-sensitized reaction of 9. Dimethyl 1-phenylethyl phosphite, 7, gives the photo-Arbuzov rearrangement product, dimethyl 1-phenylethylphosphonate (10), in 67% average yield and minor amounts (2%) of 2,3-diphenylbutane (11a) in quantum yields of 0.32 and
在乙腈,苯和环己烷中进行亚磷酸1-芳基乙基酯7、8和9的直接UV辐射,同样,在9.的亚苯撑敏化反应中也是如此。亚磷酸二甲基1-苯乙基酯7得到光-Arbuzov重排产物1-苯基乙基膦酸二甲酯(10)的平均产率为67%,少量的2%(2%)的2,3-二苯基丁烷(11a)的量子产率分别为0.32和0.02。旋光性主要为(R)-1-苯基乙基亚磷酸酯7(R / S = 97/3; 94%ee)在35-40摄氏度下的光重排在立体成因迁移碳上具有高度立体特异性,从而得到主要是(R)-10(R / S = 86/14,72 +/- 2%ee)。使用硝基氧化物自由基捕集器TEMPO可以主要从(R)-7(R / S = 97/3; 94%ee)提供膦酸酯10(大概是所有笼状产物),产率为64%(ee为80%,R / S = 90/10)。相比之下,直接辐射下的亚磷酸1-(4-乙酰苯基)-乙基酯(S)-8(S /