Development of Novel Synthetic Reactions Using Cationic Reagents

使用阳离子试剂开发新型合成反应

• 批准号: 02650619
• 负责人: HASHIMOTO Yukihiko
• 金额: $ 0.9万
• 依托单位: University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1990
• 资助国家: 日本
• 起止时间: 1990 至 1991
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02650619/
• 关键词: Cation; The Michael Reaction; The Diels-Alder Reaction; The Claisen Condensation; Stereoselective; Regioselective; Lewis Acid; クライゼン縮合; ディ-ルス・アルダ-反応; ルイス酸

2, 2-Dimethoxyethyl esters are easily transformed into 1, 3-dioxolan-2-ylium cations in situ on the action of Lewis Acid. Thus selectively monoprotected unsymmetrical 1, 3-diketones were obtained by the reaction of 2, 2-dimethoxyethyl esters with enamines in the presence of dichlorobis(trifluoromethanesulfonato)titanium. And 2, 2-dimethoxyethyl acrylate, which is easily prepared by the Mitsunobu reaction, reacts with dieties at -78ﾟC in the presence of a Lewis acid such as titanium(IV)chloride to afford the corresponding Diels-Alder adducts in high yields. Furthermore, 2-(I-alkenyl)-I, 3-dioxolan-2-ylium cations derived from 2, 2-dimethoxyethyl 2alkenoates react with enamities to predominantly give syn Michael adducts in good yields. This is the first example of such a high syn-selectivity for the Michael reaction of alpha, beta-unsaturated ester derivatives with ketone enelate equivalents.An alpha-Sulfenyl group is known to participate to the neighboring cationic center and synthetic methodologies using sulfenyl group participation was also investigated. alpha-Sulfenyl acetals reacted smoothly with silylated carbon nucleophiles such as silyl enol ether, ketene silyl acetal, and allylsilane in the presence of a catalytic amount of Lewis acid mainly to give anti-Cram adducts with high diastereoselectivity by the asymmetric induction of the alpha-sulfur atom of the acetals. As well, (alpha-Sulfenylmethyl)allyl acetates reacted with silylated carbon nucleophiles in the presence of a catalytic amount of a Lewis acid to give mainly alpha-adducts at the sulfenylmethyl group in moderate to good yields with high regioselectivity. The reaction may proceed via episulfonium ion intermediates.

在刘易斯酸的作用下，2，2-二甲氧基乙酯容易原位转化为1，3-二氧戊环-2-基阳离子。在二氯二（三氟甲磺酸根）钛存在下，2，2-二甲氧基乙酯与烯胺反应，得到选择性单保护的不对称1，3-二酮。在刘易斯酸如氯化钛（IV）存在下，2，2-二甲氧基乙基丙烯酸酯与二元醇在-78 ℃下反应，高产率地得到相应的Diels-Alder加合物。此外，2-烯基-2，2-二甲氧基乙基2-烯酸酯衍生的2-（1-烯基）-1，3-二氧戊环-2-基阳离子与烯键化合物反应，以良好的产率主要得到syn Michael加合物。这是α，β-不饱和酯衍生物与酮烯酸酯等价物的Michael反应具有如此高的顺式选择性的第一个例子。已知α-亚硫基参与邻近的阳离子中心，并且还研究了使用亚硫基参与的合成方法。在催化量的刘易斯酸存在下，α-砜基缩醛与硅烷基化的碳亲核试剂如烯醇醚、烯酮甲硅烷基缩醛和烯丙基硅烷顺利反应，主要是通过缩醛中α-硫原子的不对称诱导得到高非对映选择性的反Cram加合物。同样，乙酸（α-亚磺酰基甲基）烯丙酯与甲硅烷基化的碳亲核试剂在催化量的刘易斯酸存在下反应，以中等至良好的产率和高的区域选择性主要在亚磺酰基甲基上得到α-加合物。该反应可以经由表锍离子中间体进行。

项目成果

Yukihiko Hashimoto: "The DielsーAlder Reaction of a 2,2ーDimethoxyethyl Ester via a Cationic Intermediate" Tetrahedron Letters. 31. 5625-5628 (1990)

Yukihiko Hashimoto：“2,2-二甲氧基乙基酯通过阳离子中间体的 Diel-Alder 反应”四面体快报 31. 5625-5628 (1990)。

Shigeru Machida: "The Highly Synーselective Michael Reaction of Enamines with 2ー(1ーAlkenyl)ー1,3ーdioxyilanー2ーylium Cations Generated from 2,2ーDimethoxy 2ーAlkenoates in situ" Tetrahedron. (1991)

Shigeru Machida：“烯胺与 2,2-二甲氧基 2-链烯酸酯原位生成的 2-(1-烯基)-1,3-dioxyilan-2-ylium 阳离子的高度顺式选择性迈克尔反应”四面体 (1991)。

K.Saigo: "Facile Synthesis of Selectively Monoprotected Unsymmetrical 1,3-Diketones from 2,2-Dimethoxyethyl Esters." Synthetic Communications. 20. 2197-2202 (1990)

K.Saigo：“从 2,2-二甲氧基乙基酯中轻松合成选择性单保护的不对称 1,3-二酮。”

K.Saigo: "Anti-Cram Selective Reaction of α-Sulfenyl Acetals with Silylated Carbon Nucleophiles." Chemistry Letters. 941-944 (1990)

K. Saigo：“α-磺基缩醛与硅烷化碳亲核试剂的抗 Cram 选择性反应”，《化学快报》941-944 (1990)。

K.Saigo: "Facile Synthesis of Selectively Monoprotected Unsymmetrical 1,3ーDiketones from 2,2ーDimethoxyethyl Esters" Synthetic Communications. 20. 2197-2202 (1990)

K. Saigo：“从 2,2-二甲氧基乙基酯轻松合成选择性单保护不对称 1,3-二酮”Synthetic Communications，20. 2197-2202 (1990)。