Kinetic and Mechanistic Aspects of Atom Transfer Radical Addition (ATRA) Catalyzed by Copper Complexes with Tris(2-pyridylmethyl)amine

α-Halocarbonyls as a Valuable Functionalized Tertiary Alkyl Source

This review introduces the synthetic organic chemical value of α-bromocarbonyl compounds with tertiary carbons. This α-bromocarbonyl compound with a tertiary carbon has been used primarily only as a radical initiator in atom transfer radical polymerization (ATRP) reactions. However, with the recent development of photo-radical reactions (around 2010), research on the use of α-bromocarbonyl compounds as tertiary alkyl radical precursors became popular (around 2012). As more examples were reported, α-bromocarbonyl compounds were studied not only as radicals but also for their applications in organometallic and ionic reactions. That is, α-bromocarbonyl compounds act as nucleophiles as well as electrophiles. The carbonyl group of α-bromocarbonyl compounds is also attractive because it allows the skeleton to be converted after the reaction, and it is being applied to total synthesis. In our survey until 2022, α-bromocarbonyl compounds can be used to perform a full range of reactions necessary for organic synthesis, including multi-component reactions, cross-coupling, substitution, cyclization, rearrangement, stereospecific reactions, asymmetric reactions. α-Bromocarbonyl compounds have created a new trend in tertiary alkylation, which until then had limited reaction patterns in organic synthesis. This review focuses on how α-bromocarbonyl compounds can be used in synthetic organic chemistry.

Reactions of Mesityl Azide with Ferrocene-Based N-Heterocyclic Germylenes, Stannylenes and Plumbylenes, Including PPh2 -Functionalised Congeners

The reactivity of ferrocene-based N-heterocyclic tetrylenes [{Fe(η5 -C5 H4 -NSitBuMe2 )2 }E] (E=Ge, Sn, Pb) towards mesityl azide (MesN3 ) is compared with that of PPh2 -functionalised congeners exhibiting two possible reaction sites, namely the EII and PIII atom. For E=Ge and Sn the reaction occurs at the EII atom, leading to the formation of N2 and an EIV =NMes unit. The germanimines are sufficiently stable for isolation. The stannanimines furnish follow-up products, either by [2+3] cycloaddition with MesN3 or, in the PPh2 -substituted case, by NMes transfer from the SnIV to the PIII atom. Whereas [{Fe(η5 -C5 H4 -NSitBuMe2 )2 }Pb] and other diaminoplumbylenes studied are inert even under forcing conditions, the PPh2 -substituted congener forms an addition product with MesN3 , thus showing a behaviour similar to that of frustrated Lewis pairs. The germylenes of this study afford copper(I) complexes with CuCl, including the first structurally characterised linear dicoordinate halogenido complex [CuX(L)] with a heavier tetrylene ligand L.

Synthesis, Resolution, and Absolute Configuration of Chiral Tris(2-pyridylmethyl)amine-Based Hemicryptophane Molecular Cages

The synthesis, characterization, and chiroptical properties of a new class of hemicryptophane cages combining a cyclotriveratrylene unit and a tris(2-pyridylmethyl)amine (TPA) moiety are reported. Changing the linkers between these two units allows for the modification of the size and shape of the cavity. The synthesis is straightforward and efficient, providing gram-scale of cage compounds. The racemic mixture of each hemicryptophane host can be readily resolved by chiral HPLC, giving an easy access to the enantiopure molecular cages of which absolute configurations have been assigned by ECD spectroscopy. These new hemicryptophanes are available chemical platforms ready to use for various purposes due to the versatile metal complexation properties of the TPA unit. A Zn(II)@hemicryptophane complex has been obtained and used as a heteroditopic host for the selective recognition of zwitterionic guests.

A highly efficient Cu catalyst system for the radical reactions of α-bromocarbonyls

A Cu/TPMA and diisopropylamine system realized highly efficient atom-transfer radical reactions (substitution and cyclization). A maximum TON of up to 25 000 was achieved.

A series of organic–inorganic hybrid materials consisting of flexible organic amine modified polyoxomolybdates: synthesis, structures and properties

A series of hybrid materials consisting of Tris[(2-pyridyl)methyl]amine modified polyoxomolybdates were obtained and some complexes have efficient photocatalytic activities to degrade pararosaniline hydrochloride dye molecules.

Properties and ATRP activity of copper complexes with substituted tris(2-pyridylmethyl)amine-based ligands

Synthesis, characterization, electrochemical studies, and ATRP activity of a series of novel copper(I and II) complexes with TPMA-based ligands containing 4-methoxy-3,5-dimethyl-substituted pyridine arms were reported. In the solid state, Cu(I)(TPMA*(1))Br, Cu(I)(TPMA*(2))Br, and Cu(I)(TPMA*(3))Br complexes were found to be distorted tetrahedral in geometry and contained coordinated bromide anions. Pseudo-coordination of the aliphatic nitrogen atom to the copper(I) center was observed in Cu(I)(TPMA*(2))Br and Cu(I)(TPMA*(3))Br complexes, whereas pyridine arm dissociation occurred in Cu(I)(TPMA*(1))Br. All copper(I) complexes with substituted TPMA ligands exhibited a high degree of fluxionality in solution. At low temperature, Cu(I)(TPMA*(1))Br was found to be symmetrical and monomeric, while dissociation of either unsubstituted pyridine and/or 4-methoxy-3,5-dimethyl-substituted pyridine arms was observed in Cu(I)(TPMA*(2))Br and Cu(I)(TPMA*(3))Br. On the other hand, the geometry of the copper(II) complexes in the solid state deviated from ideal trigonal bipyramidal, as confirmed by a decrease in τ values ([Cu(II)(TPMA*(1))Br][Br] (τ = 0.92) > [Cu(II)(TPMA*(3))Br][Br] (τ = 0.77) > [Cu(II)(TPMA*(2))Br][Br] (τ = 0.72)). Furthermore, cyclic voltammetry studies indicated a nearly stepwise decrease (ΔE ≈ 60 mV) of E1/2 values relative to SCE (TPMA (-240 mV) > TPMA*(1) (-310 mV) > TPMA*(2) (-360 mV) > TPMA*(3) (-420 mV)) on going from [Cu(II)(TPMA)Br][Br] to [Cu(II)(TPMA*(3))Br][Br], confirming that the presence of electron-donating groups in the 4 (-OMe) and 3,5 (-Me) positions of the pyridine rings in TPMA increases the reducing ability of the corresponding copper(I) complexes. This increase was mostly the result of a stronger influence of substituted TPMA ligands toward stabilization of the copper(II) oxidation state (log β(I) = 13.4 ± 0.2, log β(II) = 19.3 (TPMA*(1)), 20.5 (TPMA*(2)), and 21.5 (TPMA*(3))). Lastly, ARGET ATRP kinetic studies show that with more reducing catalysts an induction period is observed. This was attributed to slow regeneration of Cu(I) species from the corresponding Cu(II).

A facile formal [2+1] cycloaddition of styrenes with alpha-bromocarbonyls catalyzed by copper: efficient synthesis of donor–acceptor cyclopropanes

The reaction of alpha-bromocarbonyls and styrenes underwent a formal [2+1] cycloaddition to produce donor–acceptor cyclopropanes.