1551-06-0Relevant articles and documents
Gas-phase heteroaromatic substitution. 8. Electrophilic attack of ethyl cation on pyrrole, N-methylpyrrole, furan, and thiophene
Laguzzi,Bucci,Grandinetti,Speranza
, p. 3064 - 3068 (1990)
Ethyl cation, obtained in the dilute gas state, together with CH5+, from the γ-radiolysis of methane, has been allowed to react with pyrrole, N-methylpyrrole, furan, and thiophene, in the pressure range 50-760 Torr and in the presence of variable concentrations of a gaseous base (NMe3). The mechanism of the substitution and of the subsequent isomerization of the relevant ionic intermediates is discussed, and the intrinsic positional selectivity of the C2H5+ ions is evaluated. Gas-phase C2H5+ ion attack on pyrroles is characterized by a significant positional selectivity toward those substrate positions with the highest net negative charge (N:α:β = 13%:10%:77% for pyrrole; α:β = 19%:81% for N-methylpyrrole). Interaction of C2H5+ with the furan center having the maximum value of the negative charge, i.e. the O atom, favors occurrence of α-substitution (α:β = 57%:43%). Thiophene displays no significant positional discrimination (α:β = 54%:46%). Gas-phase attack of C2H5+ on simple five-membered heteroaromatics is mainly governed by electrostatic interactions established within the encounter pair. This characterizes gaseous C2H5+ as a very ''hard'' electrophile, rather than a borderline acid, as expected on the grounds of the alkyl cation ''hardness'' scale. This deviation is explained in terms of the bridged geometry for C2H5+ and its effect on the LUMO energy level of the ion.
Neutrophil-Selective Fluorescent Probe Development through Metabolism-Oriented Live-Cell Distinction
Gao, Min,Lee, Sun Hyeok,Park, Sang Hyuk,Ciaramicoli, Larissa Miasiro,Kwon, Haw-Young,Cho, Heewon,Jeong, Joseph,Chang, Young-Tae
supporting information, p. 23743 - 23749 (2021/10/14)
Human neutrophils are the most abundant leukocytes and have been considered as the first line of defence in the innate immune system. Selective imaging of live neutrophils will facilitate the in situ study of neutrophils in infection or inflammation events as well as clinical diagnosis. However, small-molecule-based probes for the discrimination of live neutrophils among different granulocytes in human blood have yet to be reported. Herein, we report the first fluorescent probe NeutropG for the specific distinction and imaging of active neutrophils. The selective staining mechanism of NeutropG is elucidated as metabolism-oriented live-cell distinction (MOLD) through lipid droplet biogenesis with the help of ACSL and DGAT. Finally, NeutropG is applied to accurately quantify neutrophil levels in fresh blood samples by showing a high correlation with the current clinical method.
Scalable Wolff-Kishner Reductions in Extreme Process Windows Using a Silicon Carbide Flow Reactor
Znidar, Desiree,O'Kearney-Mcmullan, Anne,Munday, Rachel,Wiles, Charlotte,Poechlauer, Peter,Schmoelzer, Christoph,Dallinger, Doris,Kappe, C. Oliver
, p. 2445 - 2455 (2019/11/03)
A safe and scalable continuous flow strategy for Wolff-Kishner reductions that employs methanol as the solvent has been developed. The use of low-cost hydrazine as the reducing agent in combination with a caustic base provides an atom-efficient, environmentally friendly method for the deoxygenation of aldehydes and ketones to alkanes. Because of the required harsh and corrosive reaction conditions (200 °C, 50 bar), reactor materials such as stainless steel, glass, or any type of polymer have compatibility problems, rendering this process problematic on a production scale. The use of corrosion-resistant silicon carbide (SiC) as the reactor material opens up the possibility of performing Wolff-Kishner reductions on scale with a considerably improved safety profile. Methanol as the solvent significantly simplifies the workup procedure compared with the generally employed high-boiling solvents such as diethylene glycol. The continuous flow protocol was applied to a number of substrates and provided the desired products in good to high yields with space-time yields of up to 152 g L-1 h-1. In addition, a pharmaceutically valuable active pharmaceutical ingredient precursor was synthesized by employing this higherature/pressure Wolff-Kishner protocol.
