Mechanistic Analysis for Sigma-Participation Based on Silicon Effects

基于硅效应的西格玛参与机理分析

• 批准号: 01470025
• 负责人: SHIMIZU Nobujirou
• 金额: $ 4.1万
• 依托单位: Kyshu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1989
• 资助国家: 日本
• 起止时间: 1989 至 1990
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-01470025/
• 关键词: sigma-Participation; Carbocation Stability; Hyperconjugation; Solvolysis; beta-Silicon Effect; シグマ関与機構; βーケイ素効果; 炭素陽イオン; シグマ共役; βケイ素効果

Kinetics and products have been investigated in detail for the solvolysis of alpha- or beta-silyl-substituted benzylic derivatives, i. e., alpha- (pentamethyldisilanyl) benzyl halides (1), 2, 2, 3, 3-tetramethy1-2, 3-disila-1-indanyl chloride (2), 2, 2-dimethy1-2-sila-1-indanyl halides (3), 1-pheny1-2-(trimethylsily) ethyl trifluroacetate (4), 2-phenyl-1- (pentamethyldisilanyl) cyclopropyl bromide (5), and 2-phenyl-2- (trimethylsilyl) ethyl trifluroacetate (6), and other related derivatives. The following observations are instructive. (1) alpha-Silicon destabilizes the benzylic cation by 3-4 kacal/mol relative to carbon ; (2) alpha- (Disilanyl) benzyl cation and alpha- (trimethylsilylmethyl) -benzyl cation are respectively 6.2-6.8 and 7.2 kcal/mol more stable than the corresponding alpha- (trialkylsilyl) benzyl cation and alpha-alkylbenzyl cation ; (3) 1 solvolyzes via kc mechanism despite a marked rate acceleration by the beta-silyl group and a rearrangement of this group seemingly characteristic of sigma-participation ; (4) The alpha-disilanyl compound 2 in which the Si-Si bond is orthogonal to the leaving group exhibits no beta-silicon effect indicative of hyperconjugative origin for the betasillic on effect ; (5) In sigma-participated (4) or aryl-paticipated solvolysis (5), the presence of the beta-silicon allows the kc solvolysis to occur exclusively or competitively.

已经对动力学和产品进行了详细研究，以详细研究了α-或β-硅烷基溶质成立的苯二衍生物的溶解度，i。 e., alpha- (pentamethyldisilanyl) benzyl halides (1), 2, 2, 3, 3-tetramethy1-2, 3-disila-1-indanyl chloride (2), 2, 2-dimethy1-2-sila-1-indanyl halides (3), 1-pheny1-2-(trimethylsily) ethyl trifluroacetate (4), 2-苯基-1-（五甲基二苯基）环丙基溴（5）和2-苯基-2-（三甲基甲硅烷基）乙基三氟乙酸乙酯（6）和其他相关衍生物。以下观察是有启发性的。 （1）α-silicon相对于碳，将3-4的kacal/mol苯并阳离子不稳定； （2）α-（氨基烷基）苄基阳离子和α-（三甲基甲基甲二甲基） - 苯基阳离子分别分别为6.2-6.8和7.2 kcal/7.2 kcal/mol，比相应的α-（试验二甲硅烷基甲硅烷基甲硅烷基甲硅烷基甲硅烷基）苄基阳离子和α-烷基甲苯甲苯甲苯基序列更稳定。 （3）通过KC机制1溶解度，尽管Beta-Silyl组的速率加速显着，并且该组似乎是Sigma参与的特征。 （4）α-二硅烷基化合物2，其中Si-Si键与离开组正交的α-二硅烷基化合物没有表现出β-硅的效应，这表明对贝塔西氏效果的过度偶联起源； （5）在Sigma参与的（4）或芳基静态溶解度（5）中，β-硅硅的存在允许KC溶剂分析仅发生或竞争。

项目成果

N.Shimizu 他2名: "Effect of SiーSi αBonds on Stability of Adiacent Benzylic Cations." Chem.Lett.1937-1940 (1990)

N.Shimizu 和其他 2 人：“Si-Si αBonds 对邻接苯甲基阳离子稳定性的影响。Chem.Lett.1937-1940 (1990)

N.Shimzu 他4名: "Silicon Effects.III.Rates and Products for Solysis of αー(PentamethyLaisilanyl) benzyl Halides and 2,2,3,3ーTetramethy1ー2,3ーdisilaー1ーindany1 Chloride." Bull.Chem.Soc.Jpn.

N.Shimzu 和其他 4 人：“硅效应。III. α-（五甲基赖硅烷基）苄基卤化物和 2,2,3,3-四甲基 1-2,3-二硅基-1-茚满基氯化物的溶解速率和产品。” .Chem.Soc.Jpn。

N. Shimizu et al.: "Silicon Effects. III. Rates and Products for Solvolysis of alpha-(Pentamethyldisilanyl) benzyl Halides and 2, 2, 3, 3-Tetramethy1-2, 3-disila-1-indanyl Chloride. Structure and Stability of alpha-(Pentamethyldisilanyl benzyl Cation in S

N. Shimizu 等人：“硅效应。III. α-（五甲基二硅烷基）苄基卤化物和 2, 2, 3, 3-四甲基 1-2, 3-disila-1-茚满基氯的溶剂分解速率和产物。结构和

N. Shimizu et al.: "Rates and Mechanism for the Solvolysis of 2, 2-Dimethyl 2-sila-1-indanyl Bromide and alpha-Trialkylsilylbenzyl rho-Toluenesulfonates. alpha-Silicon Effect on the Stability of Benzylic Cations." Bull. Chem. Soc. Jpn.64. (1991)

N. Shimizu 等人：“2, 2-二甲基 2-sila-1-茚满基溴和 α-三烷基甲硅烷基苄基对甲苯磺酸盐的溶剂分解速率和机制。α-硅对苄基阳离子稳定性的影响。”

N.Shimizu: "Solvolysis of 2-pentamethyldishldisilanylbenzyl Halides and 2,2,3,3-Tetramethy1-2,3-disila-1-indanyl Chloride." J.Am.Chem.Soc.

N.Shimizu：“2-五甲基二硅烷基苯甲基卤化物和 2,2,3,3-四甲基 1-2,3-二硅基-1-茚满基氯的溶剂分解。”