6080-83-7Relevant academic research and scientific papers
Selective Construction of C?C and C=C Bonds by Manganese Catalyzed Coupling of Alcohols with Phosphorus Ylides
Liu, Xin,Werner, Thomas
, p. 1096 - 1104 (2020/12/31)
Herein, we report the manganese catalyzed coupling of alcohols with phosphorus ylides. The selectivity in the coupling of primary alcohols with phosphorus ylides to form carbon-carbon single (C?C) and carbon-carbon double (C=C) bonds can be controlled by the ligands. In the conversion of more challenging secondary alcohols with phosphorus ylides the selectivity towards the formation of C?C vs. C=C bonds can be controlled by the reaction conditions, namely the amount of base. The scope and limitations of the coupling reactions were thoroughly evaluated by the conversion of 21 alcohols and 15 ylides. Notably, compared to existing methods, which are based on precious metal complexes as catalysts, the present catalytic system is based on earth abundant manganese catalysts. The reaction can also be performed in a sequential one-pot reaction generating the phosphorus ylide in situ followed manganese catalyzed C?C and C=C bond formation. Mechanistic studies suggest that the C?C bond was generated via a borrowing hydrogen pathway and the C=C bond formation followed an acceptorless dehydrogenative coupling pathway. (Figure presented.).
Measurement of supramolecular effective molarities for intramolecular H-bonds in zinc porphyrin-imidazole complexes
Jinks, Michael A.,Sun, Hongmei,Hunter, Christopher A.
, p. 1440 - 1447 (2014/03/21)
The association constants for formation of 1:1 complexes between five different imidazole ligands and eight different porphyrins have been measured by UV/vis titration experiments in two different solvents, toluene and 1,1,2,2-tetrachloroethane (TCE). Ligands equipped with H-bond acceptors (ester or amide) and porphyrins equipped with H-bond donors (phenol) can make H-bonds in addition to the zinc-nitrogen coordination interaction. The free energy contributions of these H-bonds to the overall stabilities of the complexes were determined using chemical double mutant cycles. Amide-phenol H-bonds contribute up to 5 kJ mol-1 to the free energy change on complexation, and ester-phenol H-bonds contribute up to 3 kJ mol-1. Porphyrin-ligand combinations with poor geometric complementarity do not make detectable H-bonding interactions. Effective molarities (EM) for the formation of H-bonds in the complexes were estimated by comparing the equilibrium constants for formation of the intramolecular interaction with the corresponding intermolecular interaction: the values are between 3 mM and 200 mM, which is comparable to previous results obtained for porphyrin-pyridine complexes. The values of EM measured for flexible and rigid ligand systems are comparable. This suggests that there is a trade off between restriction of conformational mobility in the flexible ligands and geometric strain in the rigid ligands, which results in similar binding affinities.
Synthesis of α β,-unsaturated amide via phosphonium ylide
Jiang, Shilei,Yang, Kefeng,Yu, Xiaochun
experimental part, p. 1759 - 1767 (2009/11/30)
A series of ,-unsaturated amides were prepared by the Wittig reaction of N,N-diethylamidemethylenetriphenylphosphorane ylide with aldehydes with moderate to good yields. Copyright Taylor & Francis Group, LLC.
Ethynylphosphonium Salts, 2. A New Method for the Preparation of Ethynyltriphenylphosphonium Salts
Bestmann, Hans Juergen,Kisielowski, Lothar
, p. 1320 - 1326 (2007/10/02)
The reaction between substituted (benzoylmethylene)- and (carbamoylmethylene)triphenylphosphoranes and the adduct of bromine to triphenylphosphane in the presence of triethylamine gives rise to the formation of (phenylethynyl)- resp. (aminoethynyl)triphen
