56139-07-2Relevant articles and documents
Solvent Dependence of the Monomer–Dimer Equilibrium of Ketone-Substituted Triscatecholate Titanium(IV) Complexes
Kwamen, A. Carel N.,Jenniches, Judith,Oppel, Iris M.,Albrecht, Markus
supporting information, p. 10550 - 10554 (2020/07/24)
Hierarchical helicates based on ketone-substituted titanium(IV)triscatecholates show different monomer-dimer behavior depending on different solvents. The dimerization constants of a whole series of differently alkyl-substituted complexes is analyzed to show that the solvent has a very strong influence on the dimerization. Hereby, effects like solvophobicity/philicity, sterics, electronics of the substituents and weak side-chain—side-chain interactions seem to act in concert.
Employing Arynes for the Generation of Aryl Anion Equivalents and Subsequent Reaction with Aldehydes
Gaykar, Rahul N.,Bhunia, Anup,Biju, Akkattu T.
, p. 11333 - 11340 (2018/07/21)
Arynes are highly reactive intermediates, which are utilized for the electrophilic arylation of various X-H bonds (X = O, N, S etc.). Herein, a new synthetic strategy is demonstrated, where arynes are converted into aryl anion equivalents by treatment with phosphines and a base. The addition of phosphines to arynes form the phosphonium salts, which in the presence of a carbonate base generates the aryl anion equivalent. Subsequent addition of the aryl anions with aldehydes afforded the secondary alcohols.
Exploring the Reactivity of α-Lithiated Aryl Benzyl Ethers: Inhibition of the [1,2]-Wittig Rearrangement and the Mechanistic Proposal Revisited
Velasco, Rocío,Silva López, Carlos,Nieto Faza, Olalla,Sanz, Roberto
, p. 15058 - 15068 (2016/10/11)
By carefully controlling the reaction temperature, treatment of aryl benzyl ethers with tBuLi selectively leads to α-lithiation, generating stable organolithiums that can be directly trapped with a variety of selected electrophiles, before they can undergo the expected [1,2]-Wittig rearrangement. This rearrangement has been deeply studied, both experimentally and computationally, with aryl α-lithiated benzyl ethers bearing different substituents at the aryl ring. The obtained results support the competence of a concerted anionic intramolecular addition/elimination sequence and a radical dissociation/recombination sequence for explaining the tendency of migration for aryl groups. The more favored rearrangements are found for substrates with electron-poor aryl groups that favor the anionic pathway.
Hierarchical assembly of helicate-type dinuclear titanium(IV) complexes
Albrecht, Markus,Mirtschin, Sebastian,De Groot, Marita,Janser, Ingo,Runsink, Jan,Raabe, Gerhard,Kogej, Michael,Schalley, Christoph A.,Froehlich, Roland
, p. 10371 - 10387 (2007/10/03)
The ligands 4-7-H2 were used in coordination studies with titanium(IV) and gallium(III) ions to obtain dimeric complexes Li 4[(4-7)6Ti2] and Li6[(4/5a) 6Ga2]. The X-ray crystal structures of Li 4[(4)6Ti2], Li4[(5b) 6Ti2], and Li4[(7a)6Ti2] could be obtained. While these complexes are triply lithium-bridged dimers in the solid state, a monomer/dimer equilibrium is observed in solution by NMR spectroscopy and ESI FT-ICR MS. The stability of the dimer is enhanced by high negative charges (Ti(IV) versus Ga(III)) of the monomers, when the carbonyl units are good donors (aldehydes versus ketones and esters), when the solvent does not efficiently solvate the bridging lithium ions (DMSO versus acetone), and when sterical hindrance is minimized (methyl versus primary and secondary carbon substituents). The dimer is thermodynamically favored by enthalpy as well as entropy. ESI FT-ICR mass spectrometry provides detailed insight into the mechanisms with which monomeric triscatecholate complexes as well as single catechol ligands exchange in the dimers. Tandem mass spectrometric experiments in the gas phase show the dimers to decompose either in a symmetric (Ti) or in an unsymmetric (Ga) fashion when collisionally activated. The differences between the Ti and Ga complexes can be attributed to different electronic properties and a charge-controlled reactivity of the ions in the gas phase. The complexes represent an excellent example for hierarchical self-assembly, in which two different noncovalent interactions of well balanced strengths bring together eleven individual components into one well-defined aggregate.
