Application of stabilization effect of silyl group in radical-polar crossover reactions enabled by photoredox-neutral catalysis

2021 ◽  
Author(s):  
Naiyuan Yang ◽  
Yewen Fang ◽  
Fenfen Xu ◽  
Rong Zhou ◽  
Xiaoping Jin ◽  
...  
Keyword(s):  
Silyl Group ◽  
Group A ◽  
Stabilization Effect

Taking advantage of the stabilization effect of silyl group, a range of less investigated organosilianes could be generally accessed by means of photoredox-neutral catalysis. With halomethyl silicates as the methylene...

N-Chlorinative Ring Contraction of 1,4-Dimethoxyphthalazines via a Bicyclization/Ring-Opening Mechanism

Synthesis ◽  
2020 ◽  
Author(s):  
Jeong Kyun Im ◽  
Ilju Jeong ◽  
Jun-Ho Choi ◽  
Won-jin Chung ◽  
ByeongDo Yang ◽  
...  
Keyword(s):  
Ring Opening ◽  
Reaction Conditions ◽  
Ring Contraction ◽  
Silyl Group ◽  
Favorskii Rearrangement ◽  
Mechanistic Analysis ◽  
Group A ◽  
Overall Efficiency ◽  
Trichloroisocyanuric Acid

AbstractAn unprecedented N-chlorinative ring contraction of 1,2-diazines was discovered and investigated with an electrophilic chlorinating reagent, trichloroisocyanuric acid (TCICA). Through optimization and mechanistic analysis, the assisting role of n-Bu4NCl as an exogenous nucleophile was identified, and the optimized reaction conditions were applied to a range of 1,4-dimethoxyphthalazine derivatives. Also, an improvement of overall efficiency was demonstrated by the use of a labile O-silyl group. A bicyclization/ring-opening mechanism, inspired by the Favorskii rearrangement, was proposed and supported by the DFT calculations. Furthermore, the efforts on scope expansion as well as the evaluation of other electrophilic promoters revealed that the newly developed ring contraction reactivity is a unique characteristic of 1,4-dimethoxyphthalazine scaffold and TCICA.

ChemInform Abstract: The Sisyl (tris(Trimethylsilyl)silyl) Group: A Fluoride Resistant, Photolabile Alcohol Protecting Group.

ChemInform ◽  
2010 ◽  
Vol 29 (2) ◽  
pp. no-no
Author(s):  
M. A. BROOK ◽  
C. GOTTARDO ◽  
S. BALDUZZI ◽  
M. MOHAMED
Keyword(s):  
Protecting Group ◽  
Silyl Group ◽  
Group A

Control of Stereochemistry by σ-Participation of a Silyl Group. A Novel Method for Diastereoselective Polyol Synthesis

1997 ◽  
Vol 62 (13) ◽  
pp. 4206-4207 ◽  
Author(s):  
Keiji Tanino ◽  
Naoei Yoshitani ◽  
Fumiko Moriyama ◽  
Isao Kuwajima
Keyword(s):  
Polyol Synthesis ◽  
Silyl Group ◽  
Group A ◽  
Novel Method

ChemInform Abstract: Control of Stereochemistry by σ-Participation of a Silyl Group. A Novel Method for Diastereoselective Polyol Synthesis.

ChemInform ◽  
2010 ◽  
Vol 28 (45) ◽  
pp. no-no
Author(s):  
K. TANINO ◽  
N. YOSHITANI ◽  
F. MORIYAMA ◽  
I. KUWAJIMA
Keyword(s):  
Polyol Synthesis ◽  
Silyl Group ◽  
Group A ◽  
Novel Method

Ti(III)-Mediated Radical-Induced Approach to a Bicyclic δ-Lactone with a Bridgehead β-Hydroxy Group

Synthesis ◽  
2018 ◽  
Vol 50 (15) ◽  
pp. 3006-3014 ◽  
Author(s):  
Tushar Chakraborty ◽  
Dipendu Das ◽  
Hina Khan
Keyword(s):  
Natural Products ◽  
Hydroxy Group ◽  
Intramolecular Cyclization ◽  
High Yield ◽  
Potential Utility ◽  
Synthetic Route ◽  
Silyl Group ◽  
Epoxide Opening ◽  
Group A ◽  
Bicyclic Lactone

Herein, we portray a synthetic route to a bicyclic lactone containing a bridgehead hydroxy group, a structure that is present in many natural products of biological and medicinal relevance. Ethyl (E)-3-(dimethylphenylsilyl)-7,8-epoxyoct-2-enoate underwent radical-mediated­ reductive epoxide opening with concomitant intramolecular cyclization using Cp2Ti(III)Cl to give cis-6-(dimethylphenylsilyl)-3-oxabicyclo[4.3.0]nonan-4-one, a bicyclic lactone with a bridgehead silyl group serving as a masked hydroxy group. Furthermore, the bridgehead C–Si bond underwent stereoretentive oxidative cleavage to give cis-6-hydroxy-3-oxabicyclo[4.3.0]nonan-4-one in high yield under Tamao–Fleming oxidation conditions; this demonstrates the potential utility of this strategy in the synthesis of many natural products bearing similar hydroxylated bridgehead chiral center embedded in a bicyclic lactone framework.

The sisyl (tris(trimethylsilyl)silyl) group: A fluoride resistant, photolabile alcohol protecting group

1997 ◽  
Vol 38 (40) ◽  
pp. 6997-7000 ◽  
Author(s):  
Michael A. Brook ◽  
Christine Gottardo ◽  
Sonya Balduzzi ◽  
Mustafa Mohamed
Keyword(s):  
Protecting Group ◽  
Silyl Group ◽  
Group A

Electron microscopic radioautographic studies on the incorporation of 3H proline in the glomerular basement membrane (GBM) in antistreptococcal-cell-membrane (SCM) injected mice

1984 ◽  
Vol 42 ◽  
pp. 188-189
Author(s):  
R.P. Nayyar ◽  
C.F. Lange ◽  
J. L. Borke
Keyword(s):  
Body Weight ◽  
Cell Membrane ◽  
Basement Membrane ◽  
Glomerular Basement Membrane ◽  
Mesangial Matrix ◽  
Electron Microscopic ◽  
Group A ◽  
Injection Protocol

Streptococcal cell membrane (SCM) antiserum injected mice show a significant thickening of glomerular basement membrane (GBM) and an increase in mesangial matrix within 4 to 24 hours of antiserum administration (1,2,3). This study was undertaken to evaluate the incorporation of 3H proline into glomerular cells and GBM under normal and anti-SCM induced conditions. Mice were administered, intraperitoneally, 0.1 ml of normal or anti-SCM serum followed by a 10 µC/g body weight injection of 3H proline. Details of the preparation of anti-SCM (Group A type 12 streptococcal pyogenes) and other sera and injection protocol have been described elsewhere (2). After 15 minutes of isotope injection a chase of cold proline was given and animal sacrificed at 20 minutes, 1,2,4,8,24 and 48 hours. One of the removed kidneys was processed for immunofluorescence, light and electron microscopic radioautographic studies; second kidney was used for GBM isolation and aminoacid analysis.

An ultrastructural study of sertoli cells in two geographically isolated populations of Aphanius dispar

1992 ◽  
Vol 50 (1) ◽  
pp. 548-549
Author(s):  
Taber A. Ba-Omar ◽  
Philip F. Prentis
Keyword(s):  
Ultrastructural Level ◽  
Uranyl Acetate ◽  
Freshwater Teleost ◽  
Isolated Populations ◽  
En Bloc ◽  
The North ◽  
Group A ◽  
Ultrathin Sections ◽  
Group B ◽  
Geographically Isolated

We have recently carried out a study of spermiogenic differentiation in two geographically isolated populations of Aphanius dispar (freshwater teleost), with a view to ascertaining variation at the ultrastructural level. The sampling areas were the Jebel Al Akhdar in the north (Group A) and the Dhofar region (Group B) in the south. Specimens from each group were collected, the testes removed, fixed in Karnovsky solution, post fixed in OsO, en bloc stained with uranyl acetate and then routinely processed to Agar 100 resin, semi and ultrathin sections were prepared for study.

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