scholarly journals Mechanistic study of the ligand controlled regioselectivity in iridium catalyzed C–H borylation of aromatic imines

RSC Advances ◽  
2018 ◽  
Vol 8 (62) ◽  
pp. 35453-35460 ◽  
Author(s):  
Yuhua Liu ◽  
Jipei Chen ◽  
Kangsheng Zhan ◽  
Yiqiang Shen ◽  
Hui Gao ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
Dft Calculation ◽  
Mechanistic Study ◽  
Aromatic Imines

DFT calculation indicates that in iridium catalyzed C–H borylation of aromatics, the ortho selectivity is proposed to be attributed to the electron donating effect of AQ ligand, while the meta selectivity is due to steric hindrance of TMP ligand.

Para-Selective Borylation of Monosubstituted Arenes Using a Transient Mediator

2019 ◽  
Author(s):  
Jie Wu ◽  
Xiao-Yue Chen ◽  
Yichen Wu ◽  
Daoming Wang ◽  
Peng Wang
Keyword(s):  
Radical Cation ◽  
Steric Hindrance ◽  
Mechanistic Study ◽  
Salt Formation ◽  
Sulfonium Salt ◽  
Trifluoromethanesulfonic Anhydride ◽  
In Situ Generation

Herein, we conceptualized a transient mediator approach that has the capability of <i>para</i>-selective C–H functionalization of monosubstituted aromatics. This approach is enabled by in situ generation of a versatile sulfonium salt via highly electrophilic phenoxathiine or thianthrene radical cation intermediate which can be readily generated from its sulfoxide with trifluoromethanesulfonic anhydride. Preliminary mechanistic study unveiled that the remarkable <i>para</i> selectivity is related to the incredible electrophilicity and steric hindrance of phenoxathiine or thianthrene radical cation. The versatility of this approach was demonstrated via <i>para</i>-borylation of various monosubstituted simple aromatics combining the sulfonium salt formation with further photocatalyzed transformation.

Para-Selective Borylation of Monosubstituted Arenes Using a Transient Mediator

2019 ◽  
Author(s):  
Jie Wu ◽  
Xiao-Yue Chen ◽  
Yichen Wu ◽  
Daoming Wang ◽  
Peng Wang
Keyword(s):  
Radical Cation ◽  
Steric Hindrance ◽  
Mechanistic Study ◽  
Salt Formation ◽  
Sulfonium Salt ◽  
Trifluoromethanesulfonic Anhydride ◽  
In Situ Generation

Herein, we conceptualized a transient mediator approach that has the capability of <i>para</i>-selective C–H functionalization of monosubstituted aromatics. This approach is enabled by in situ generation of a versatile sulfonium salt via highly electrophilic phenoxathiine or thianthrene radical cation intermediate which can be readily generated from its sulfoxide with trifluoromethanesulfonic anhydride. Preliminary mechanistic study unveiled that the remarkable <i>para</i> selectivity is related to the incredible electrophilicity and steric hindrance of phenoxathiine or thianthrene radical cation. The versatility of this approach was demonstrated via <i>para</i>-borylation of various monosubstituted simple aromatics combining the sulfonium salt formation with further photocatalyzed transformation.

Intermolecular steric hindrance in 7-acylamino-[1H]-2-oxo-1,8-naphthyridines: NMR, ESI-MS, IR, and DFT calculation studies

2011 ◽  
Vol 22 (5) ◽  
pp. 1143-1151 ◽  
Author(s):  
Borys Ośmiałowski ◽  
Erkki Kolehmainen ◽  
Elina Kalenius ◽  
Babita Behera ◽  
Reijo Kauppinen ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
Dft Calculation ◽  
Esi Ms

Mechanistic study of proliferation induced by Angelica sinensis in gastric epithelial cells

2001 ◽  
Vol 120 (5) ◽  
pp. A145-A145
Author(s):  
C CHO ◽  
Y YE ◽  
E LIU ◽  
V SHIN ◽  
N SHAM
Keyword(s):  
Epithelial Cells ◽  
Mechanistic Study ◽  
Angelica Sinensis ◽  
Gastric Epithelial Cells

Steric hindrance influence of a diazo link upon mesogenic properties of some ligands and related copper complexes

1997 ◽  
Vol 94 ◽  
pp. 1695-1714 ◽  
Author(s):  
P Lesot ◽  
F Perez ◽  
P Judeinstein ◽  
JP Bayle ◽  
H Allouchi ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
Copper Complexes

Mechanistic study on the cardioprotective and chemosensitizing effects of a novel danshensu derivative

Planta Medica ◽  
2014 ◽  
Vol 80 (16) ◽  
Author(s):  
L Wang ◽  
L Shan ◽  
G Cui ◽  
Y Chen ◽  
J li ◽  
...  
Keyword(s):  
Mechanistic Study

METABOLISM OF 17α-HYDROXYPROGESTERONE-4-14C-17α-CAPROATE BY HOMOGENATES OF RAT LIVER AND HUMAN PLACENTA

1961 ◽  
Vol 36 (4) ◽  
pp. 511-519 ◽  
Author(s):  
Margaret Wiener ◽  
Charles I. Lupa ◽  
E. Jürgen Plotz
Keyword(s):  
Rat Liver ◽  
Human Placenta ◽  
Steric Hindrance ◽  
Placental Tissue ◽  
Caproic Acid ◽  
Major Product ◽  
Side Chain ◽  
Anaerobic Conditions ◽  
Prolonged Action ◽  
Long Acting

ABSTRACT 17α-hydroxyprogesterone-4-14C-17α-caproate (HPC), a long-acting progestational agent, was incubated with homogenates of rat liver and human placenta. The rat liver was found to reduce Ring A of HPC under anaerobic conditions to form allopregnane-3β,17α-diol-20-one-17α-caproate and pregnane-3β,17α-diol-20-one-17α-caproate, the allopregnane isomer being the major product. The caproic acid ester was neither removed nor altered during the incubation. Placental tissue did not attack HPC under conditions where the 20-ketone of progesterone was reduced. It is postulated that this absence of attack on the side chain is due to steric hindrance from the caproate ester, and that this may account for the prolonged action of HPC.

Tyrosine-Selective Bioconjugation with Iminoxyl Radicals

2020 ◽  
Author(s):  
Katsuya Maruyama ◽  
Takashi Ishiyama ◽  
Yohei Seki ◽  
Kounosuke Oisaki ◽  
Motomu Kanai
Keyword(s):  
Reaction Time ◽  
Steric Hindrance ◽  
Room Temperature ◽  
Water Soluble ◽  
Light Irradiation ◽  
Sodium Ascorbate ◽  
Iminoxyl Radical ◽  
Short Reaction Time ◽  
Modified Peptides ◽  
The Stability

A novel Tyr-selective protein bioconjugation using the water-soluble persistent iminoxyl radical is described. The conjugation proceeded with high Tyr-selectivity and short reaction time under biocompatible conditions (room temperature in buffered media under air). The stability of the conjugates was tunable depending on the steric hindrance of iminoxyl. The presence of sodium ascorbate and/or light irradiation promoted traceless deconjugation, restoring the native Tyr structure. The method is applied to the synthesis of a protein-dye conjugate and further derivatization to azobenzene-modified peptides.

Synthesis of Conjugated Triynes via Alkyne Metathesis

2019 ◽  
Author(s):  
Idriss Curbet ◽  
Sophie Colombel-Rouen ◽  
Romane Manguin ◽  
Anthony Clermont ◽  
Alexandre Quelhas ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
High Selectivity ◽  
Alkyne Metathesis ◽  
Cross Metathesis ◽  
Synthetic Strategy ◽  
Sterically Hindered ◽  
Site Selective

<div> <div> <div> <div> <p>The synthesis of conjugated triynes by molybdenum-catalyzed alkyne metathesis is reported. Strategic to the success of this approach is the utilization of sterically-hindered diynes that allowed for the site- selective alkyne metathesis to produce the desired con- jugated triyne products. The steric hindrance of alkyne moiety was found to be crucial in preventing the for- mation of diyne byproducts. This novel synthetic strategy was amenable to self- and cross-metathesis providing straightforward access to the corresponding symmetrical and dissymmetrical triynes with high selectivity. </p> </div> </div> </div> </div>

Sign in / Sign up

Export Citation Format

Share Document