54912-31-1Relevant academic research and scientific papers
Lewis acid promoted double bond migration in O-allyl to Z-products by Ru-H complexes
Wang, Haibin,Liu, Shaodong,Sun, Tingting,Lv, Zhanao,Zhan, Zhen,Yin, Guochuan,Chen, Zhuqi
, p. 10 - 17 (2019/03/11)
In catalytic double bond migration reaction, E-configuration olefins were normally generated as the dominant product because E-configuration was thermodynamically favored. However, Z-configuration products are sometimes desired in pharmaceutical chemistry owing to the structure-activity relationship. In this paper, we have demonstrated a new strategy that Lewis acid promoted an widely employed and convenient ruthenium(II) complex for the catalytic isomerization of O-allylethers, leading to thermodynamic-unfavored Z-product under mild conditions. The model substrate of allyl phenyl ether can be simply scaled up to 20 mmol to produce Z-product with TON of 2453 and TOF of 13,430 h?1 at 40–60 °C. The system of Ru(II)/Lewis Acid catalysts was suitable for various substituted O-allylethers and other types of substrates. Through mechanism study including kinetic study, ligand inhibition effect and molecular spectroscopy, the dissociation of PPh3 ligand by the addition of Lewis acid, and the formation a five-membered Ru complex from anchimeric assistance were both recognized as essential steps to improve the reactivity and to control the stereoselectivity of catalytic double bond migration reaction through metal hydride addition-elimination mechanism. This new strategy may provide a new opportunity to produce thermodynamic-unfavored product in heterocyclic compounds for pharmaceutical chemistry.
Ruthenium(IV)-catalyzed isomerization of the C=C bond of O-allylic substrates: A theoretical and experimental study
Varela-Ulvarez, Adrian,Sordo, Jose A.,Piedra, Estefania,Nebra, Noel,Cadierno, Victorio,Gimeno, Jose
experimental part, p. 10583 - 10599 (2011/11/06)
A general mechanism to rationalize RuIV-catalyzed isomerization of the C=C bond in O-allylic substrates is proposed. Calculations supporting the proposed mechanism were performed at the MPWB1K/6-311+G(d,p)+SDD level of theory. All experimental observations in different solvents (water and THF) and under different pH conditions (neutral and basic) can be interpreted in terms of the new mechanism. Theoretical analysis of the transformation from precatalyst to catalyst led to structural identification of the active species in different media. The experimentally observed induction period is related to the magnitudes of the energy barriers computed for that process. The theoretical energy profile for the catalytic cycle requires application of relatively high temperatures, as is experimentally observed. Participation of a water molecule in the reaction coordinate is mechanistically essential when the reaction is carried out in aqueous medium.
Thermodynamic, spectroscopic, and density functional theory studies of allyl aryl and prop-1-enyl aryl ethers. Part 1. Thermodynamic data of isomerization
Taskinen, Esko
, p. 1824 - 1834 (2007/10/03)
A chemical equilibration study of the relative thermodynamic stabilities of seventy isomeric allyl aryl ethers (a) and (Z)-prop-1-enyl aryl ethers (b) in DMSO solution has been carried out. From the variation of the equilibrium constant with temperature the Gibbs energies, enthalpies, and entropies of isomerization at 298.15 K have been evaluated. Because of their low enthalpies, the (Z)-prop-1-enyl aryl ethers are strongly favored at equilibrium, the Gibbs energies of the a→b isomerization ranging from -12 to -23 kJ mol-1. The entropy contribution is negligible in most reactions, but occasionally small positive values less than +10 J K-1 mol-1 of the entropy of isomerization are found. The equilibration studies were also extended to involve two pairs of related isomeric ethers with a Me substituent on C(2) of the olefinic bond. The Me substituent was found to increase the relative thermodynamic stability of the allylic ethers by ca. 3.4 kJ mol-1.
Study of metal and acid catalysed deprotection of propargyl ethers of alcohols via their allenyl ethers
Mereyala, Hari Babu,Gurrala, Srinivas Reddy,Mohan, S. Krishna
, p. 11331 - 11342 (2007/10/03)
A new method for the deprotection of prop-2-ynyl ethers 1b-9b is described. Isomerisation of 1b-9b to O-allenyl ethers 1d-9d and deprotection by reaction with Hg(OCOCF3)2, aq.HCl, aq.CF3CO2H and best by use of a catalytic amount of OsO4 is described to obtain the alcohols 1a-9a in good yield. Application of this method for the deprotection of prop-2-enyl ethers 7c,8c,10c-13c via their corresponding prop-1-enyl ethers 7e,8e,10e-13e to obtain the corresponding alcohols 7a,8a,10a-13a is also described.
