σ-πChelation-Controlled Stereoselective Hydrosilylation of Ketones

σ-π螯合控制的酮立体选择性氢化硅烷化

• 批准号: 13640588
• 负责人: ASAO Naoki
• 金额: $ 0.32万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640588/
• 关键词: Lewis acid; Triple bond; Chelation; π-Coordination; σ-Coordination; Stereoselectivity; σ-π型キレーション; 立体選択性; ヒドロシリル化反応; ヒドロシリル反応

Hydrosilylation of 2-methyl-1-phenyl-pentan-1-one with Et_3SiH in the presence of catalytic amounts of B(C_6F_5)_3 gave the anti-product, (1R^*,2R^*)-2-methyl-1-phenyl-1-triethylsilyloxy-pentane, with slight predominance over syn-product. In contrast, the syn-product, (4R^*,5S^*)-4-methyl-5-phenyl-5-triethylsilyloxypent-1-yne, was obtained stereoselectively in the reaction of 2-methyl-1-phenyl-pent-4-yn-1-one. The investigation of other related systems also supported the above result; the reduction of 2-methyl-3-alkynyl aryl ketones or 2-methyl-3-alkynyl alkyl ketones with R_3SiH/cat. B(C_6F_5)_3 produced the corresponding syn-alcohols either exclusively or predominantly, while the reduction of the saturated analogue, 2-methyl-1-phenyl aryl ketone, with the same reducing agent afforded the corresponding anti-alcohol. The observed anti-selectivity in the latter case can be explained by the ordinary Felkin-Anh model. On the other hand, the unusual syn-selectivities can be accounted for by the σ-π chelation by R_3Si^+, in which both the lone pair (σ) of the carbonyl group and the π-electrons of the alkyne coordinate to the silylium ion.

在催化量的B（C_6F_5）_3存在下，2-甲基-1-苯基-1-戊酮与Et_3SiH进行硅氢加成反应，得到反式产物（1 R ^*，2 R ^*）-2-甲基-1-苯基-1-三乙基硅氧基戊烷，其含量略高于顺式产物。与此相反，在2-甲基-1-苯基-N-甲基-4-炔-1-酮的反应中立体选择性地得到了合成产物（4 R ^*，5S ^*）-4-甲基-5-苯基-5-三乙基硅氧基戊-1-炔。对其它相关体系的研究也支持了上述结果：2-甲基-3-炔基芳基酮或2-甲基-3-炔基烷基酮用R_3SiH/cat. B（C_6F_5）_3还原，只或主要生成相应的顺式醇，而饱和类似物2-甲基-1-苯基芳基酮用相同的还原剂还原，则生成相应的反式醇。在后一种情况下观察到的反选择性可以用普通的Felkin-Anh模型来解释。另一方面，这种不寻常的顺式选择性可以通过R_3Si^+的σ-π螯合作用来解释，在这种作用中，羰基的孤对电子（σ）和炔的π-电子都与硅鎓离子配位。

项目成果

N. Asao, K. Nabatame, Y. Yamamoto: "Lewis Acid mediated intermolecular vinylsilylation of alkynes"Chem. Lett.. 982-983 (2001)

N. Asao，K. Nabatame，Y. Yamamoto：“路易斯酸介导的炔烃分子间乙烯基甲硅烷基化”Chem。

N.Asao, T.Shimada, T.Shimada, Y.Yamamoto: "Lewis Acid Catalyzed Stereoselective Carbosilylation. Intramolecular trans-Vinylsilylation and trans-Arylsilylation of Unactivated Alkynes"J. Am. Chem. Soc.. 123. 10899-10902 (2001)

N.Asao，T.Shimada，T.Shimada，Y.Yamamoto：“路易斯酸催化的立体选择性碳硅烷化。未活化炔烃的分子内反式乙烯基硅烷化和反式芳基硅烷化”J。

N.Asao, T.Oishi, K.Sato, Y.Yamamoto: "Lewis acid catalyzed stereoselective hydrosilylation of ketones under the control of σ-πchelation"Tetrahedron. 58. 8195-8203 (2002)

N.Asao、T.Oishi、K.Sato、Y.Yamamoto：“在 σ-π 螯合控制下的路易斯酸催化酮的立体选择性氢化硅烷化”Tetrahedron 58. 8195-8203 (2002)

N. Asao, T. Ohishi, K. Sato, Y. Yamamoto: "σ-π Chelation-Controlled Stereoselective Hydrosilylation of Ketones"J. Am. Chem. Soc.. 123. 6931-6932 (2001)

N. Asao、T. Ohishi、K. Sato、Y. Yamamoto：“酮的 σ-π 螯合控制立体选择性氢化硅烷化” J. Am. 123. 6931-6932 (2001)

K.Imamura, E.Yoshikawa, V.Gevorgyan, T.Sudo, N.Asao, Y.Yamamoto: "Lewis acid-mediated intramolecular addition of silyl enol ethers to internal unactivated alkynes"Can. J. Chem.. 79. 1624-1631 (2001)

K.Imamura、E.Yoshikawa、V.Gevorgyan、T.Sudo、N.Asao、Y.Yamamoto：“刘易斯酸介导的硅烯醇醚分子内加成到内部未活化的炔烃”可以。