Exploratory Studies of H-Atom Abstraction and Silyl-Transfer Photoreactions of Silylalkyl Ketones and (Silylalkyl)phthalimides
摘要:
Exploratory studies have been conducted to probe competitive H-atom abstraction and SET-promoted, silyl-transfer reactions of excited states of silylalkyl ketones and (silylalkyl)phthalimides. Photochemical investigations with the (silylalkyl)phthalimides have demonstrated that typical gamma-H atom abstraction reactions occur upon irradiation in less polar and less silophilic solvents. In contrast, irradiation of these substances in polar-protic-silophilic solvents results in product formation via pathways involving SET-induced desilylation. Photoreactions of silylamido-aryl ketones in either nonsilophilic or silophilic solvents take place almost exclusively by sequential SET silyl-transfer routes to produce azetidine products. Finally, the chemical selectivities of photochemical reactions of silylpropyl-aryl ketones appear to depend on medium polarity and silophilicity. Irradiation of these substrates in less polar-nonsilophilic solvents leads to almost exclusive formation of acetophenone and vinyltrimethylsilane in essentially equal yields by a reaction pathway initiated by gamma-H atom abstraction and 1,4-biradical fragmentation. However, irradiation of these substances in polar-silophilic solvents produces acetophenone and vinyltrimethylsilane in an ca. 1.7:1 ratio reflecting the fact that a silyl-transfer pathway competes with H-atom abstraction under these conditions.
Exploratory Studies of H-Atom Abstraction and Silyl-Transfer Photoreactions of Silylalkyl Ketones and (Silylalkyl)phthalimides
摘要:
Exploratory studies have been conducted to probe competitive H-atom abstraction and SET-promoted, silyl-transfer reactions of excited states of silylalkyl ketones and (silylalkyl)phthalimides. Photochemical investigations with the (silylalkyl)phthalimides have demonstrated that typical gamma-H atom abstraction reactions occur upon irradiation in less polar and less silophilic solvents. In contrast, irradiation of these substances in polar-protic-silophilic solvents results in product formation via pathways involving SET-induced desilylation. Photoreactions of silylamido-aryl ketones in either nonsilophilic or silophilic solvents take place almost exclusively by sequential SET silyl-transfer routes to produce azetidine products. Finally, the chemical selectivities of photochemical reactions of silylpropyl-aryl ketones appear to depend on medium polarity and silophilicity. Irradiation of these substrates in less polar-nonsilophilic solvents leads to almost exclusive formation of acetophenone and vinyltrimethylsilane in essentially equal yields by a reaction pathway initiated by gamma-H atom abstraction and 1,4-biradical fragmentation. However, irradiation of these substances in polar-silophilic solvents produces acetophenone and vinyltrimethylsilane in an ca. 1.7:1 ratio reflecting the fact that a silyl-transfer pathway competes with H-atom abstraction under these conditions.
An intermolecularanti-Markovnikovhydroamination of alkenes has been developed using triethyl phosphite and N-hydroxyphthalimide. The process tolerates a wide range of alkenes, including vinyl ethers, silanes, and sulfides as well as electronically unbiased terminal and internal alkenes. The resultant N-alkylphthalimides can readily be transformed to the corresponding primary amines. Mechanistic probes
Regioselective Radical Alkene Amination Strategies by Using Phosphite-Mediated Deoxygenation
作者:Samuel W. Lardy、Valerie A. Schmidt
DOI:10.1055/s-0037-1611911
日期:2019.11
frameworks is a highly sought-after goal. Presented here is a summary of recent efforts conducted by our group to develop radical-mediated amination strategies for the formal synthesis of primary amines from alkenes with exclusive anti-Markovnikov regioselectivity. We have found that N-hydroxyphthalimide is an effectivereagent capable of supplying both the N and H atoms for alkene hydroamination in
含氮化合物是所有化学学科的基本主题,这些框架的有效合成是一个备受追捧的目标。这里介绍的是我们小组最近为开发自由基介导的胺化策略而进行的工作的总结,该策略用于从具有独家抗马尔科夫尼科夫区域选择性的烯烃正式合成伯胺。我们发现 N-羟基邻苯二甲酰亚胺是一种有效的试剂,能够在基团转移自由基加成型机制中为烯烃加氢胺化提供 N 和 H 原子。此外,烯丙基氧邻苯二甲酰亚胺衍生物同样能够进行自由基基团转移并允许外部烯烃的氨基烯丙基化。
The operation of H-atom and TMS-group transfer processes in the photochemistry of silylamidoalkyl- and silylalkyl-ketones and -phthalimides
作者:Yean Jang Lee、Chao Pin Lee、Yoon Tag Jeon、Patrick S. Mariano、Ung Chan Yoon、Dong Uk Kim、Jack C. Kim、Jong Gun Lee
DOI:10.1016/s0040-4039(00)73797-x
日期:1993.9
Exploratory Studies of H-Atom Abstraction and Silyl-Transfer Photoreactions of Silylalkyl Ketones and (Silylalkyl)phthalimides
作者:Yean Jang Lee、Rong Ling、Patrick S. Mariano、Ung Chan Yoon、Dong Uk Kim、Sun Wha Oh
DOI:10.1021/jo9522623
日期:1996.1.1
Exploratory studies have been conducted to probe competitive H-atom abstraction and SET-promoted, silyl-transfer reactions of excited states of silylalkyl ketones and (silylalkyl)phthalimides. Photochemical investigations with the (silylalkyl)phthalimides have demonstrated that typical gamma-H atom abstraction reactions occur upon irradiation in less polar and less silophilic solvents. In contrast, irradiation of these substances in polar-protic-silophilic solvents results in product formation via pathways involving SET-induced desilylation. Photoreactions of silylamido-aryl ketones in either nonsilophilic or silophilic solvents take place almost exclusively by sequential SET silyl-transfer routes to produce azetidine products. Finally, the chemical selectivities of photochemical reactions of silylpropyl-aryl ketones appear to depend on medium polarity and silophilicity. Irradiation of these substrates in less polar-nonsilophilic solvents leads to almost exclusive formation of acetophenone and vinyltrimethylsilane in essentially equal yields by a reaction pathway initiated by gamma-H atom abstraction and 1,4-biradical fragmentation. However, irradiation of these substances in polar-silophilic solvents produces acetophenone and vinyltrimethylsilane in an ca. 1.7:1 ratio reflecting the fact that a silyl-transfer pathway competes with H-atom abstraction under these conditions.