On February 23, 2009, Shishkov, Igor V.; Rominger, Frank; Hofmann, Peter published an article.Synthetic Route of 29704-38-9 The title of the article was Remarkably stable copper(I) α-carbonyl carbenes: synthesis, structure, and mechanistic studies of alkene cyclopropanation reactions. And the article contained the following:
Copper(I) iminophosphinamido α-acylcarbene complexes were prepared by ligand substitution of η2-ethene complex with 2-aryl diazoacetate esters and diazoacetamides; crystal structure, thermal decomposition and cyclopropanation kinetics were examined Reaction of [[tBu2P(NSiMe3)2κN,κN’]Cu(η2-C2H4)] (1) with 4-R1C6H4C(N2)COR2 [7a-g; R1 = NO2, OMe; R2 = OEt, OtBu, NMe2, OMe, OCH(1,4-C6H4Cl)2] gave the corresponding carbene complexes [[tBu2P(NSiMe3)2κN,κN’]Cu:C(COR2)-1,4-C6H4R1] (8a-g) whereas 2-diazo-N,N-diisopropylacetamide was unreactive. The rotation barriers around the Cu-Ccarbene and Ccarbene-CAr bonds or their low limits were determined for some of these compounds by 1H-VT-NMR spectroscopy. Carbene 8g [R1 = OMe, R2 = OCH(p-Cl-C6H4)2] was isolated in anal. pure, crystalline form as the first stable representative of this important class of compounds Its solid-state mol. structure revealed an orthogonal position of the carbene fragment relative to both the ligand plane and the ester C:O group and a remarkably short Cu-Ccarbene distance of 1.822(4) Å. Compound 8g reacted with styrene stereoselectively to give the corresponding trans-cyclopropane derivative and [tBu2P(NSiMe3)2-κ2N]Cu(η2-CH2:CHPh). The stoichiometric cyclopropanation of styrene with 8g and the previously described diarylcarbene [[tBu2P(NSiMe3)2-κ2N]Cu:C(p-NO2C6H4)2] (6) in toluene-d8 revealed that the reactions are first order in both the copper carbenes and the alkene. The activation parameters for 8g (ΔH⧧ = 51.5(9) kJ mol-1 and ΔS⧧ = -127.1(28) J mol-1 K-1) and for 6 (ΔH⧧ = 53.4(8) kJ mol1- and ΔS⧧ = -152.1(23) J mol-1 K-1) were derived from the kinetics of the cyclopropanation processes. Thermal decomposition of carbene 8g in toluene-d8 displayed first-order kinetics until 20-25% conversion with activation parameters ΔH⧧ = 85.5(24) kJ mol-1 and ΔS⧧ = -49.0(76) J mol-1 K-1. Solutions of 6 in toluene-d8 also decompose in a first-order fashion with ΔH⧧ = 66.1(20) kJ mol-1 and ΔS⧧ = -125.5(56) J mol-1 K-1. A Hammett study employing 8g and para-substituted styrenes afforded ρ = -1.06(19), demonstrating the electrophilic nature of α-carbonyl copper(I) carbene (Fischer-type) complexes. The electronic structure of 8 with R1 = R2 = OMe was investigated by DFT methods. The experimental process involved the reaction of tert-Butyl 2-(4-nitrophenyl)acetate(cas: 29704-38-9).Synthetic Route of 29704-38-9
The Article related to copper carbene acylcarbene carboxycarbene complex preparation cyclopropanation kinetics, thermal decomposition kinetics copper acylcarbene carboxycarbene complex, diazoacetate diazoacetamide aryl complexation copper carbene complex preparation structure, crystal structure copper iminophosphinamide acylcarbene complex and other aspects.Synthetic Route of 29704-38-9
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