Effect of Amino Substituents on the Stereochemical Outcome of the Photo-Arbuzov Rearrangements of 1-Arylethyl Phosphorodiamidites
作者:Worawan Bhanthumnavin、Wesley G. Bentrude
DOI:10.1021/jo040297+
日期:2005.6.1
with radicals 3 in the solvent cage with retained configuration at carbon (40% percent net retention, eq 5). The yield of product 10 is reduced to 54%, and 12a is absent. Similarly, the five-membered ring naphthylethyl analogue, phosphorodiamidite 9 (R/S = 98:2), affords largely (R)-11 with apparent 34 ± 3% net retention. The degree of stereorandomization observed in these systems is higher than was reported
用紫外光在乙腈,苯和环己烷中辐照基本立体化学纯的1-芳基乙二磷酰胺8和9(表1-4)。建议通过碳-氧键断裂形成的单线自由基对进行反应(方案1),其寿命比类似亚磷酸酯5和6更长。基于消耗的8%(表1和表4),四甲基1-苯基乙基亚磷酰胺基二磷酸酯(8)以59%±2%的GC收率生成光Arbuzov重排产物10,以及自由基二聚产物2,3-二苯基丁烷12a,其数量相当于 19%的潜在形成的1-苯基乙基基团。类似地,由9产生的光重排产物11的产率为64±4%(表2和表4),而1-萘基乙基的18b + 2%的可计量性为12b。的立体化学的photorearrangement富集8(- [R /小号= 99:1),得到10,其中表观67±2%(100 Ý,公式3,表4)的初始自由基对[ 3,14 ]再结合与配置的保持在立体碳上(34±3%净保留,当量5)。使用TEMPO时70%(100ÿ,公式3)的初始1