1200-14-2Relevant articles and documents
ESR line shape studies of N (4-n butyl benzilidine) 4-amino 2,2,6,6-tetramethyl piperidine 1-oxide (BBTMPO) in toluene
Hwang, J. S.,Pollet, P.,Saleem, M. M.
, p. 577 - 583 (1986)
BBTMPO was synthesized by a condensation of 4-n butyl benzaldehyde and 4-amino 2,2,6,6- tetramethyl piperidine N oxide (4-tempamine).The shape of the resulting spin probe, estimated using the Dreiding models, is a spherocone of length 10.7 Angstroem capped by hemispheres of radii 6.6 and 4.0 Angstroem, respectively.The magnetic parameters of BBTMPO in toluene at 77 K were determined.Variable temperature ESR line shape studies in the temperature range of 142-211 K revealed that BBTMPO exhibited anisotropic rotational ditFusion in toluene along the long axis of the spherocone and in the direction parallel to the N-O bond.Rotational diffusion along the long axis was found to be 3+/-0.5 and 7+/-0.5 times faster for frozen and liquid toluene, respectively, than the other two axes.The line shapes have been simulated by using the stochastic Liouville theory of slow-motional effects on ESR spectrum.The slow tumbling spectrum (158 K) in the model-sensitive region showed good agreement for a Brownian model.The plot of τR vs 1/T over the whole temperature range yield a good linear fit with two slopes, with the activation energy for reorientation process of 4.9 kcal/mol in the liquid state, and 9.9 kcal/mol in the solid state.The higher activation energy of rotational reorientation coupled with a lower anisotropy of molecular reorientation (N) in the solid state, indicates that the rotational degrees of freedom is more restricted in the frozen state than in the liquid state.Molecular reorientation for BBTMPO in toluene was analyzed in terms of the hydrodynamic free space model for molecular relaxation in liquids.The stickiness factor S was found to be 0.6 while the anisotropic interaction parameter K which measures the coupling of rotation to translation was found to be 0.7.For perdeuterated 2,2,6,6-tetramethyl-4-piperidine N-oxide (PD-Tempone) in toluene the stickiness factor was calculated to be 0.3, and κ was 0.4.The doubling in size and weight in going from PD-Tempone to BBTMPO increases the stickiness factor and K from 0.3 to 0.6, and 0.4 to 0.7, respectively.The similarity in the structure of BBTMPO to that of liquid crystal methoxy benzilidine butyl aniline (MBBA) and its potential use as a spin probe for MBBA is discussed.
Scalable Negishi Coupling between Organozinc Compounds and (Hetero)Aryl Bromides under Aerobic Conditions when using Bulk Water or Deep Eutectic Solvents with no Additional Ligands
Dilauro, Giuseppe,Azzollini, Claudia S.,Vitale, Paola,Salomone, Antonio,Perna, Filippo M.,Capriati, Vito
supporting information, p. 10632 - 10636 (2021/04/09)
Pd-catalyzed Negishi cross-coupling reactions between organozinc compounds and (hetero)aryl bromides have been reported when using bulk water as the reaction medium in the presence of NaCl or the biodegradable choline chloride/urea eutectic mixture. Both C(sp3)-C(sp2) and C(sp2)-C(sp2) couplings have been found to proceed smoothly, with high chemoselectivity, under mild conditions (room temperature or 60 °C) in air, and in competition with protonolysis. Additional benefits include very short reaction times (20 s), good to excellent yields (up to 98 %), wide substrate scope, and the tolerance of a variety of functional groups. The proposed novel protocol is scalable, and the practicability of the method is further highlighted by an easy recycling of both the catalyst and the eutectic mixture or water.
Acceptorless Dehydrogenation of Alcohols Catalyzed by CuI N-Heterocycle Thiolate Complexes
Tan, Da-Wei,Li, Hong-Xi,Zhang, Meng-Juan,Yao, Jian-Lin,Lang, Jian-Ping
, p. 1113 - 1118 (2017/03/27)
CuI N-heterocycle thiolate clusters efficiently catalyze the acceptorless dehydrogenation of alcohols at 70 °C. A variety of secondary/primary benzylic, allylic, and aliphatic alcohols are dehydrogenated to the corresponding ketones and aldehydes in high yields of isolated product upon release of H2. This simple catalytic system is involved in the synthesis of imines through the one-pot reaction of alcohols and amines.
Destruction and Construction: Application of Dearomatization Strategy in Aromatic Carbon-Nitrogen Bond Functionalization
Wang, Shuo-En,Wang, Linfei,He, Qiuqin,Fan, Renhua
, p. 13655 - 13658 (2015/11/11)
The formation of carbon-carbon bonds through the functionalization of aromatic carbon-nitrogen bonds is a highly attractive synthetic strategy in the synthesis of aromatic molecules. In this paper, we report a novel aromatic carbon-nitrogen bond functionalization reaction by using a simple dearomatization strategy. Through this process para-substituted anilines serve as a potential aryl source in the construction of a range of functionalized aromatic molecules, such as quaternary carbon centers, α-keto esters, and aldehydes.