FREE-RADICAL ACETOXY GROUP MIGRATION
FREE-RADICAL ACETOXY GROUP MIGRATION
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DOI：
10.1021/ja01054a068
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发表时间：
1969-01-01
影响因子：
15
通讯作者：
LAW, FCP
中科院分区：
文献类型：
--
作者：
TANNER, DD;LAW, FCP
CO、CH3 7 (8%) 分别生成二甲酸和二乙酸，提供了进一步的表征。在40℃下用带有Pyrex过滤器的高压Hanovia 450-W灯照射1在甲醇-四氢呋喃(4:1)中，并通过制备型硅胶薄层色谱法分离产物，得到eri/zro-甲基2, 3-二苯基-3-甲氧基丙酸酯(2)，苏-甲基2, 3-二苯基-3-甲氧基丙酸酯(3)，甲基α-肉桂酸苯酯 (4) 和二苯乙炔 (5)（方案 I）。产品4、5通过与正品样品对比鉴定；产品2和3通过光谱数据进行表征； 2：IR（CC14）1733cm-1（0=0）； nmr (CC14) 6.78（单峰，3 H）、6.29（单峰，3）、5.40、6.35（AB 模式，7= 11 Hz，2 H）、2.92（宽单峰，10 H）；质谱：270处有非常小的母峰(<0.1%)，基峰121，精确质量，计算值：270.12557，实测值：270.12557±0.00264； uv（甲醇）Xmax 252 µ (e 7000)； 3：ir(CC14)1733cm-1(C=0)； nmr (CC14) 6.98（单峰，3）、6.61（单峰，3 H）、5.43、6.30（AB 模式，J= 9 Hz，2 H）；质谱：270处有非常小的母峰(<0.1%)，基峰121，精确质量，计算值：270.12557，实测值：270.12557±0.00264； uv（甲醇）Xmax 252 µ (e 7150)。在用甲醇钠的甲醇溶液处理后，2和3转化为4。确定在该反应条件下4是光稳定的并且真实的二苯基环丙烯酮定量地脱羰成二苯基乙炔。在类似条件下，在甲苯中光解 1，并通过制备型硅胶薄层色谱分离，分离出主要产物 5（方案 I）。为了确定 5 是否来自二苯基环丙烯酮，用单色汞蒸气灯在 40 A 下以 4360 A 和 No. 2 Sylvania 光驱在 40 下照射 1，在该条件下发现真正的二苯基环丙烯酮稳定。使用任一光源均可分离出二苯基环丙烯酮，且不含二苯基乙炔痕迹 (5)。 1 在甲醇氧化银中分解，过滤并通过制备型硅胶薄层色谱分离，分离出α-苯基肉桂酸甲酯 (4)、二苯基环丙烯酮 (6) 和苯甲酰基苯基乙酸甲酯 (7)，所有这些均通过与真实样品的比较进行鉴定。结果表明，在该反应条件下，6部分转化为4（方案I）。 1 的甲醇氯化亚铜分解也产生少量 6。在甲醇光解中，产物 2、3 和 4 似乎是通过沃尔夫重排过程产生的。 2 和 3 远超 4 表明了它们的起源
CO, CH3 7 (8%) which generated the diformate and diacetate, respec-tively, provided further characterization. Irradiation of 1 in methanol-tetrahydrofuran (4: 1) at—40 with a high-pressure Hanovia 450-W lamp with a Pyrex filter and separation of the products by preparative silica gel thin layer chromatography yielded eryi/zro-methyl 2, 3-diphenyl-3-methoxypropionate (2), threo-methyl 2, 3-diphenyl-3-methoxypropionate (3), methyl a-phenylcinnamate (4), and diphenylacetylene (5)(Scheme I). Products 4 and 5 were identified by comparison with authentic samples; products 2 and 3 were characterized by spectral data; 2: ir (CC14) 1733 cm-1 (0= 0); nmr (CC14) 6.78 (singlet, 3 H), 6.29 (singlet, 3), 5.40, 6.35 (AB pattern,. 7= 11 Hz, 2 H), 2.92 (broad singlet, 10 H); mass spectrum: very small parent peak (< 0.1%) at 270, base peak 121, exact mass, caled: 270.12557, found: 270.12557±0.00264; uv (methanol) Xmax 252 µ (e 7000); 3: ir (CC14) 1733 cm-1 (C= 0); nmr (CC14) 6.98 (singlet, 3), 6.61 (singlet, 3 H), 5.43, 6.30 (AB pattern, J= 9 Hz, 2 H); mass spectrum: very small parent peak (< 0.1%) at 270, base peak 121, exact mass, caled: 270.12557, found: 270.12557±0.00264; uv (methanol) Xmax 252 µ (e 7150). Upon treatment with sodium methoxide in methanol 2 and 3 were converted into 4. It was determined that under the reaction conditions 4 is photostable and authentic diphenylcyclopropenone decarbonylates quantitatively to diphenylacetylene. Photolysis of 1 in toluene under similar conditions and separation by preparative silica gel thin layer chromatography resulted in isolation of 5 as the major product (Scheme I).In order to determine whether 5 arises from diphenylcyclopropenone, 1 was irradiated at—40 with a mono-chromatic mercury vapor lamp at 4360 A and with a No. 2 Sylvania photoflood, conditions at which authen-tic diphenylcyclopropenone was found to be stable. Using either light source, diphenylcyclopropenone was isolated with no trace of diphenylacetylene (5). Decomposition of 1 in methanolic silver oxide, filtration, and separation by preparative silica gel thin layer chromatography resulted in isolation of methyl a-phenylcinnamate (4), diphenylcyclopropenone (6), and methyl benzoylphenylacetate (7), all identified by com-parison with authentic samples. It was shown that under the reaction conditions, 6 is partially converted into 4 (Scheme I). Methanolic cuprous chloride de-composition of 1 also produced a small amount of 6. In the methanol photolysis, products 2, 3, and 4 appear to arise via a Wolff rearrangement process. That 2 and 3 greatly predominated over 4 suggests their origin