32211-88-4

Upstream product

• 85-44-9 phthalic anhydride 

Downstream Products

• 58417-74-6 N-(1,1-dimethyl-2-oxo-2-phenyl-ethyl)-phthalimide 
• 14463-79-7 2-methyl-2-phthalimidopropanoic acid 
• 401846-08-0 N,N’-(1,2-phenylene)bis(2-(1,3-dioxoisoindolin-2-yl)-2-methylpropanamide) 

Relevant academic research and scientific papers

Development of modifiable bidentate amino oxazoline directing group for Pd-catalyzed arylation of secondary C-H bonds

Abstract A novel bidentate α-amino oxazolinyl directing group has been developed. Different from previous directing groups, this newly designed directing group was easily prepared from amino acids and modified in structure. This auxiliary preferentially effects functionalization at secondary C(sp3)-H bonds, rather than at aryl C(sp2)-H bonds. The diastereoselectivity of direct arylation between geminal secondary C(sp3)-H bonds in linear molecules has also been realized for the first time with a chiral directing group by remote chirality relay. Two diastereoisomers are produced with the same chiral source by changing the substituents of substrates and aryl halides. A new direction: A multifunctional amino oxazoline directing group that is readily available from amino acids, has been developed, which can induce chemo-, regio- and diastereoselectivity in secondary C(sp3)-H arylation reactions. Furthermore, this directing group is removable and modifiable. Steric control and counterions play important roles in the relayed chirality transfer.

Ligand Redox Noninnocence in [CoIII(TAML)]0/- Complexes Affects Nitrene Formation

The redox noninnocence of the TAML scaffold in cobalt-TAML (tetra-amido macrocyclic ligand) complexes has been under debate since 2006. In this work, we demonstrate with a variety of spectroscopic measurements that the TAML backbone in the anionic complex [CoIII(TAMLred)]- is truly redox noninnocent and that one-electron oxidation affords [CoIII(TAMLsq)]. Multireference (CASSCF) calculations show that the electronic structure of [CoIII(TAMLsq)] is best described as an intermediate spin (S = 1) cobalt(III) center that is antiferromagnetically coupled to a ligand-centered radical, affording an overall doublet (S = 1/2) ground-state. Reaction of the cobalt(III)-TAML complexes with PhINNs as a nitrene precursor leads to TAML-centered oxidation and produces nitrene radical complexes without oxidation of the metal ion. The ligand redox state (TAMLred or TAMLsq) determines whether mono-or bis-nitrene radical complexes are formed. Reaction of [CoIII(TAMLsq)] or [CoIII(TAMLred)]- with PhINNs results in the formation of [CoIII(TAMLq)(Na￠Ns)] and [CoIII(TAMLq)(Na￠Ns)2]-, respectively. Herein, ligand-to-substrate single-electron transfer results in one-electron-reduced Fischer-type nitrene radicals (Na￠Ns-) that are intermediates in catalytic nitrene transfer to styrene. These nitrene radical species were characterized by EPR, XANES, and UV-vis spectroscopy, high-resolution mass spectrometry, magnetic moment measurements, and supporting CASSCF calculations.

Enantioselective Hydroxylation of Benzylic C(sp3)-H Bonds by an Artificial Iron Hydroxylase Based on the Biotin-Streptavidin Technology

The selective hydroxylation of C-H bonds is of great interest to the synthetic community. Both homogeneous catalysts and enzymes offer complementary means to tackle this challenge. Herein, we show that biotinylated Fe(TAML)-complexes (TAML = Tetra Amido Macrocyclic Ligand) can be used as cofactors for incorporation into streptavidin to assemble artificial hydroxylases. Chemo-genetic optimization of both cofactor and streptavidin allowed optimizing the performance of the hydroxylase. Using H2O2 as oxidant, up to ～300 turnovers for the oxidation of benzylic C-H bonds were obtained. Upgrading the ee was achieved by kinetic resolution of the resulting benzylic alcohol to afford up to >98% ee for (R)-tetralol. X-ray analysis of artificial hydroxylases highlights critical details of the second coordination sphere around the Fe(TAML) cofactor.

Redox-Active Ligand Assisted Multielectron Catalysis: A Case of CoIII Complex as Water Oxidation Catalyst

Water oxidation is the key step in both natural and artificial photosynthesis to capture solar energy for fuel production. The design of highly efficient and stable molecular catalysts for water oxidation based on nonprecious metals is still a great challenge. In this article, the electrocatalytic oxidation of water by Na[(L4-)CoIII], where L is a substituted tetraamido macrocyclic ligand, was investigated in aqueous solution (pH 7.0). We found that Na[(L4-)CoIII] is a stable and efficient homogeneous catalyst for electrocatalytic water oxidation with 380 mV onset overpotential in 0.1 M phosphate buffer (pH 7.0). Both ligand- and metal-centered redox features are involved in the catalytic cycle. In this cycle, Na[(L4-)CoIII] was first oxidized to [(L2-)CoIIIOH] via a ligand-centered proton-coupled electron transfer process in the presence of water. After further losing an electron and a proton, the resting state, [(L2-)CoIIIOH], was converted to [(L2-)CoIV=O]. Density functional theory (DFT) calculations at the B3LYP-D3(BJ)/6-311++G(2df,2p)//B3LYP/6-31+G(d,p) level of theory confirmed the proposed catalytic cycle. According to both experimental and DFT results, phosphate-assisted water nucleophilic attack to [(L2-)CoIV=O] played a key role in O-O bond formation.

Unifying Evaluation of the Technical Performances of Iron-Tetra-amido Macrocyclic Ligand Oxidation Catalysts

The main features of iron-tetra-amido macrocyclic ligand complex (a sub-branch of TAML) catalysis of peroxide oxidations are rationalized by a two-step mechanism: FeIII + H2O2 → Active catalyst (Ac) (kI), and Ac + Substrate (S) → FeIII + Product (kII). TAML activators also undergo inactivation under catalytic conditions: Ac → Inactive catalyst (ki). The recently developed relationship, ln(S0/S∞) = (kII/ki)[FeIII]tot, where S0 and S∞ are [S] at time t = 0 and ∞, respectively, gives access to ki under any conditions. Analysis of the rate constants kI, kII, and ki at the environmentally significant pH of 7 for a broad series of TAML activators has revealed a 6 orders of magnitude reactivity differential in both kII and ki and 3 orders differential in kI. Linear free energy relationships linking kII with ki and kI reveal that the reactivity toward substrates is related to the instability of the active TAML intermediates and suggest that the reactivity in all three processes derives from a common electronic origin. The reactivities of TAML activators and the horseradish peroxidase enzyme are critically compared.

Pd(II)-catalyzed C(sp3)-H arylation of amino acid derivatives with click-triazoles as removable directing groups

By using click-triazoles as conveniently approachable and removable directing groups, the direct palladium-catalyzed C(sp3)-H arylation of amino acid derivatives with various aryl iodides bearing different electronic properties has been achieved. Notably, the desired amino acid molecule can be obtained by the cleavage of the tethered click-triazoles after the catalytic reaction, which aims to provide a practical protocol for the accessibility of both natural and synthetic amino acids.

Synthesis and characterization of Co(iii) amidoamine complexes: Influence of substituents of the ligand on catalytic cyclic carbonate synthesis from epoxide and carbon dioxide

A series of amidoamine ligands (1) and their cobalt(iii) complexes (2) were synthesized and characterized by various spectroscopic techniques including 1H-NMR and X-ray crystallographic techniques. X-ray crystallography shows that one of the complexes, 2a, forms a chiral coordination polymer due to bridge formation with Li+ associated with the complex, although the ligand is achiral. Complex 2 was employed for catalytic synthesis of cyclic carbonates from epoxides and carbon dioxide (CO2) in a solvent free condition. A strong influence of the substituents on the ligand 1 was revealed by the varied activity of complex 2. The presence of electron withdrawing groups such as chloro (2b) and nitro (2c) increases the Lewis acidity of the catalyst, which, in turn, enhances the catalytic activity of 2. An electron withdrawing group containing complexes (2b and 2c) showed exceptionally high catalytic activity with a turnover frequency (TOF) of 662 and 602 h-1 respectively at 130°C and 300 psig CO2 pressure. On the other hand, our studies indicate that a catalyst with an electron releasing group (2d) showed relatively lower activity with a TOF of 488 h-1 under similar reaction conditions. Our results show that cobalt(iii) complexes follow the reactivity order of 2d 2a 2c 2b.

Specific Inhibitors in Vitamin Biosynthesis. Part 7. Syntheses of Blocked 7,8-Dihydropteridines via &α-Amino Ketones

The synthesis of 15 blocked 7,8-dihydropteridines is described in which the pyrazine ring is built from a derivative of an α-amino ketone.Three routes to the amino ketones based upon amino acids, nitrosyl chloride addition to alkenes, and nitro alcohols are discussed.The compounds synthesised are inhibitors of 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase , an enzyme in the pathway leading to dihydrofolate, and the inhibitory potencies of the compounds are discussed in the light of a hypothetical active site model for the enzyme.