Chiral (Iminophosphoranyl)ferrocenes: A New Class of Practical Ligands for Rhodium-Catalyzed Asymmetric Hydrogenation
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- 作者：Thanh Thien Co ; Sang Chul Shim ; Chan Sik Cho ; Tae-Jeong Kim ; Sang Ook Kang ; Won-Sik Han ; Jaejung Ko ; and Chung-Kyun Kim
- 刊名：Organometallics
- 出版年：2005
- 出版时间：September 26, 2005
- 年：2005
- 卷：24
- 期：20
- 页码：4824 - 4831
- 全文大小：188K
- 年卷期：v.24,no.20(September 26, 2005)
- ISSN：1520-6041
文摘
A series of new chiral (iminophosphoranyl)ferrocenes, {
5-C5H4-(PPh2=N-2,6-R2-C6H3)}Fe{5-C5H3-1-PPh2-2-CH(Me)(Y)} (1a, Y = NMe2, R = Me; 1b, Y = NMe2, R = iPr; 1c, Y =OMe, R = iPr), {5-C5H4-(PPh2=N-2,6-R2-C6H3)}Fe{5-C5H3-1-(PPh2=N-2,6-R2-C6H3)-2-CH(Me)(Y)} (2a, R = Me, Y = NMe2; 2b, R = iPr, Y = NMe2,; 2c, R = Me, Y = OMe), and(5-C5H5)Fe{5-C5H4-1-PR2-2-CH(Me)N=PPh3} (3a, R = Ph; 3b, R = C6H11), have beenprepared from the reaction of 1,1'-bis(diphenylphosphino)-2-[(dimethylamino)ethyl]ferrocenewith aryl azides (1 and 2) and the reaction of phosphine dichlorides (R3PCl2) with 1,1'-bis(diphenylphosphino)-2-(aminoethyl)ferrocene (3), respectively. They form rhodium complexesof the type [Rh(NBD)(L)]ClO4 (4-6; L = 1-3), where the ligand (L) adopts an 2(N,N) (2) or2(P,N) mode (3), as expected. In the case of 1, a potential tridentate species, however, achelating bidentate mode through the -CH(Me)NMe2 and -PPh2 groups is realized withthe exclusion of the -P=NAr group from the coordination sphere, as confirmed by the X-raycrystal structure of [Rh(NBD)(1b)]ClO4 (4b). The new ligands (1-3) exhibit exceptionallyhigh enantioselectivity (up to 99%) and catalytic activity in the Rh-catalyzed asymmetrichydrogenation of (E)-2-methylcinnamic acid, (Z)-2-acetamidocinnamate, and (Z)-2-acetamidoacrylate.
5-C5H4-(PPh2=N-2,6-R2-C6H3)}Fe{5-C5H3-1-PPh2-2-CH(Me)(Y)} (1a, Y = NMe2, R = Me; 1b, Y = NMe2, R = iPr; 1c, Y =OMe, R = iPr), {5-C5H4-(PPh2=N-2,6-R2-C6H3)}Fe{5-C5H3-1-(PPh2=N-2,6-R2-C6H3)-2-CH(Me)(Y)} (2a, R = Me, Y = NMe2; 2b, R = iPr, Y = NMe2,; 2c, R = Me, Y = OMe), and(5-C5H5)Fe{5-C5H4-1-PR2-2-CH(Me)N=PPh3} (3a, R = Ph; 3b, R = C6H11), have beenprepared from the reaction of 1,1'-bis(diphenylphosphino)-2-[(dimethylamino)ethyl]ferrocenewith aryl azides (1 and 2) and the reaction of phosphine dichlorides (R3PCl2) with 1,1'-bis(diphenylphosphino)-2-(aminoethyl)ferrocene (3), respectively. They form rhodium complexesof the type [Rh(NBD)(L)]ClO4 (4-6; L = 1-3), where the ligand (L) adopts an 2(N,N) (2) or2(P,N) mode (3), as expected. In the case of 1, a potential tridentate species, however, achelating bidentate mode through the -CH(Me)NMe2 and -PPh2 groups is realized withthe exclusion of the -P=NAr group from the coordination sphere, as confirmed by the X-raycrystal structure of [Rh(NBD)(1b)]ClO4 (4b). The new ligands (1-3) exhibit exceptionallyhigh enantioselectivity (up to 99%) and catalytic activity in the Rh-catalyzed asymmetrichydrogenation of (E)-2-methylcinnamic acid, (Z)-2-acetamidocinnamate, and (Z)-2-acetamidoacrylate.