Asymmetric Inter- and Intramolecular Cyclopropanation of Alkenes Catalyzed by Chiral Ruthenium Porphyrins. Synthesis and Crystal Structure of a Chiral Metalloporphyrin Carbene Complex
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- 作者：Chi-Ming Che ; Jie-Sheng Huang ; Fu-Wa Lee ; Yan Li ; Tat-Shing Lai ; Hoi-Lun Kwong ; Pang-Fei Teng ; Wing-Sze Lee ; Wai-Cheung Lo ; Shie-Ming Peng ; and Zhong-Yuan Zhou
- 刊名：Journal of the American Chemical Society
- 出版年：2001
- 出版时间：May 9, 2001
- 年：2001
- 卷：123
- 期：18
- 页码：4119 - 4129
- 全文大小：161K
- 年卷期：v.123,no.18(May 9, 2001)
- ISSN：1520-5126
文摘
Extensive investigations of asymmetric intermolecular cyclopropanation of terminal alkenes withdiazoacetates catalyzed by ruthenium porphyrin [Ru(P*)(CO)(EtOH)] (1, H2P* = 5,10,15,20-tetrakis{(1S,4R,5R,8S)-1,2,3,4,5,6,7,8-octahydro-1,4:5,8-dimethanoanthracene-9-yl}porphyrin) and the application ofcatalyst 1 to asymmetric intramolecular cyclopropanation of allylic or homoallylic diazoacetates are described.The intermolecular cyclopropanation of styrene and its derivatives with ethyl diazoacetate afforded thecorresponding cyclopropyl esters in up to 98% ee with high trans/cis ratios of up to 36 and extremely highcatalyst turnovers of up to 1.1 × 104. Examination of the effects of temperature, diazoacetate, solvent, andsubstituent in the intermolecular cyclopropanation reveals that (i) both enantioselectivity and trans selectivityincrease with decreasing temperature, (ii) sterically encumbered diazoacetates N2CHCO2R, such as R = But,and donor solvents, such as diethyl ether and tetrahydrofuran, are beneficial to the trans selectivity, and (iii)electron-donating para substituents on styrene accelerate the cyclopropanations, with the log(kX/kH) vs 
+ plotfor para-substituted styrenes p-X-C6H4CH=CH2 (X = MeO, Me, Cl, CF3) exhibiting good linearity with asmall negative 
+ value of -0.44 ± 0.09. In the case of intramolecular cyclopropanation, complex 1 promotedthe decomposition of a series of allylic diazoacetates to form the cyclopropyl lactones in up to 85% ee,contributing the first efficient metalloporphyrin catalyst for an asymmetric intramolecular cyclopropanation.Both the inter- and intramolecular cyclopropanations were proposed to proceed via a reactive chiral rutheniumcarbene intermediate. The enantioselectivities in these processes were rationalized on the basis of the X-raycrystal structures of closely related stable chiral carbene complexes [Ru(P*)(CPh2)] (2) and [Ru(P*)(C(Ph)CO2CH2CH=CH2)] (3) obtained from reactions of complex 1 with N2CPh2 and N2C(Ph)CO2CH2CH=CH2,respectively.
+ plotfor para-substituted styrenes p-X-C6H4CH=CH2 (X = MeO, Me, Cl, CF3) exhibiting good linearity with asmall negative + value of -0.44 ± 0.09. In the case of intramolecular cyclopropanation, complex 1 promotedthe decomposition of a series of allylic diazoacetates to form the cyclopropyl lactones in up to 85% ee,contributing the first efficient metalloporphyrin catalyst for an asymmetric intramolecular cyclopropanation.Both the inter- and intramolecular cyclopropanations were proposed to proceed via a reactive chiral rutheniumcarbene intermediate. The enantioselectivities in these processes were rationalized on the basis of the X-raycrystal structures of closely related stable chiral carbene complexes [Ru(P*)(CPh2)] (2) and [Ru(P*)(C(Ph)CO2CH2CH=CH2)] (3) obtained from reactions of complex 1 with N2CPh2 and N2C(Ph)CO2CH2CH=CH2,respectively.