Metal-free [3+2] cycloaddition of azides with Tf2CCH2 for the regioselective preparation of elusive 4-(trifluoromethylsulfonyl)-1,2,3-triazoles

2015 ◽  
Vol 51 (32) ◽  
pp. 6992-6995 ◽  
Author(s):  
Benito Alcaide ◽  
Pedro Almendros ◽  
Carlos Lázaro-Milla
Keyword(s):  
Room Temperature ◽  
Metal Free

1,2-Dipole Tf2CCH2 is generated in situ from 2-(2-fluoro-pyridin-1-ium-1-yl)-1,1-bis[(trifluoromethyl)-sulfonyl]ethan-1-ide and immediately reacted at room temperature with azides to afford previously unknown 4-trifluoromethanesulfonyl 1,2,3-triazoles in a highly regio- and chemoselective fashion.

Metal-free phosphonation of heteroarene N-oxides with trialkyl phosphite at room temperature

2017 ◽  
Vol 15 (15) ◽  
pp. 3165-3169 ◽  
Author(s):  
Ming-Tao Chen ◽  
Xia You ◽  
Li-Gang Bai ◽  
Qun-Li Luo
Keyword(s):  
Room Temperature ◽  
Trialkyl Phosphite ◽  
Metal Free ◽  
Mild Conditions ◽  
Short Time

Heteroarene N-oxides were successfully converted to heteroarylphosphonates in a very short time under mild conditions through in situ activation with CBrCl3.

scholarly journals Transition-metal-free synthesis of aryl 1-thioglycosides with arynes at room temperature

RSC Advances ◽  
2021 ◽  
Vol 11 (43) ◽  
pp. 26666-26671
Author(s):  
Yao Liu ◽  
Xiao-Bing Yu ◽  
Xiang-Mei Zhang ◽  
Qian Zhong ◽  
Li-Hua Liao ◽  
...  
Keyword(s):  
Transition Metal ◽  
Room Temperature ◽  
Metal Free

We have developed a convenient and transition-metal-free protocol for the synthesis of aryl 1-thioglycosides in good to excellent yields via the arynes generated in situ combined with glycosyl thiols.

Metal-free efficient thiolation of C(sp2) functionalization via in situ-generated NHTS for the synthesis of novel sulfenylated 2-aminothiazole and imidazothiazole

2021 ◽  
Vol 45 (10) ◽  
pp. 4632-4637
Author(s):  
Shuddhodan N. Kadam ◽  
Ajay N. Ambhore ◽  
Rahul D. Kamble ◽  
Mahesh G. Wakhradkar ◽  
Priya D. Gavhane ◽  
...  
Keyword(s):  
Room Temperature ◽  
Metal Free

A direct metal-free approach for the synthesis of novel sulfenylated 2-aminothiazole and imidazothiazole derivatives at room temperature is reported via an in situ-generated electrophilic thiolating agent.

Metal-Free One-Pot Chemoselective Thiocyanation of Imidazothiazoles and 2-Aminothiazoles with in situ Generated N-Thiocyanatosuccinimide

Synlett ◽  
2018 ◽  
Vol 29 (14) ◽  
pp. 1902-1908 ◽  
Author(s):  
Bhaskar Dawane ◽  
Shuddhodan Kadam ◽  
Ajay Ambhore ◽  
Madhav Hebade ◽  
Rahul Kamble ◽  
...  
Keyword(s):  
Nucleophilic Substitution ◽  
Electrophilic Substitution ◽  
Room Temperature ◽  
Reaction Conditions ◽  
One Pot ◽  
Metal Free ◽  
Excellent Yield

A chemoselective thiocyanation of imidazothiazoles and 2-aminothiazoles with use of in situ generated N-thiocyanatosuccinimide (NTS) at room temperature is described. The protocol offers mild reaction conditions and high chemoselectivity for electrophilic substitution in imidazothiazoles over nucleophilic substitution. This method provides metal-free and easy conversion of imidazothiazoles and 2-aminothiazoles into their corresponding C-3 and C-5 thiocyanates, respectively, in good to excellent yield. The present protocol also offers the effective thiocyanation of bifunctional imidazothiazoles containing ­aliphatic –OH and C(sp2)–H bond functionalities.

Otoconia perfect/imperfect crystals

1994 ◽  
Vol 52 ◽  
pp. 42-43
Author(s):  
César D. Fermin ◽  
Dale Martin
Keyword(s):  
Image Processing ◽  
Room Temperature ◽  
Phosphotungstic Acid ◽  
Gallus Domesticus ◽  
Crystal Matrix ◽  
Organic Templates ◽  
Image Processing Algorithms ◽  
Processing Algorithms ◽  
Diffraction Patterns

Otoconia of higher vertebrates are interesting biological crystals that display the diffraction patterns of perfect crystals (e.g., calcite for birds and mammal) when intact, but fail to produce a regular crystallographic pattern when fixed. Image processing of the fixed crystal matrix, which resembles the organic templates of teeth and bone, failed to clarify a paradox of biomineralization described by Mann. Recently, we suggested that inner ear otoconia crystals contain growth plates that run in different directions, and that the arrangement of the plates may contribute to the turning angles seen at the hexagonal faces of the crystals.Using image processing algorithms described earlier, and Fourier Transform function (2FFT) of BioScan Optimas®, we evaluated the patterns in the packing of the otoconia fibrils of newly hatched chicks (Gallus domesticus) inner ears. Animals were fixed in situ by perfusion of 1% phosphotungstic acid (PTA) at room temperature through the left ventricle, after intraperitoneal Nembutal (35mg/Kg) deep anesthesia. Negatives were made with a Hitachi H-7100 TEM at 50K-400K magnifications. The negatives were then placed on a light box, where images were filtered and transferred to a 35 mm camera as described.

In Situ Localization of PPAR Gamma and Uncoupling Protein in Mouse Embryo Sections Using Digoxigenin-Labeled Riboprobes

1996 ◽  
Vol 54 ◽  
pp. 32-33
Author(s):  
C. Jennermann ◽  
S. A. Kliewer ◽  
D. C. Morris
Keyword(s):  
Alkaline Phosphatase ◽  
Room Temperature ◽  
Uncoupling Protein ◽  
Ppar Gamma ◽  
Nuclear Hormone Receptor ◽  
Full Length ◽  
Northern Analysis ◽  
Peroxisome Proliferator

Peroxisome proliferator-activated receptor gamma (PPARg) is a member of the nuclear hormone receptor superfamily and has been shown in vitro to regulate genes involved in lipid metabolism and adipocyte differentiation. By Northern analysis, we and other researchers have shown that expression of this receptor predominates in adipose tissue in adult mice, and appears first in whole-embryo mRNA at 13.5 days postconception. In situ hybridization was used to find out in which developing tissues PPARg is specifically expressed.Digoxigenin-labeled riboprobes were generated using the Genius™ 4 RNA Labeling Kit from Boehringer Mannheim. Full length PPAR gamma, obtained by PCR from mouse liver cDNA, was inserted into pBluescript SK and used as template for the transcription reaction. Probes of average size 200 base pairs were made by partial alkaline hydrolysis of the full length transcripts. The in situ hybridization assays were performed as described previously with some modifications. Frozen sections (10 μm thick) of day 18 mouse embryos were cut, fixed with 4% paraformaldehyde and acetylated with 0.25% acetic anhydride in 1.0M triethanolamine buffer. The sections were incubated for 2 hours at room temperature in pre-hybridization buffer, and were then hybridized with a probe concentration of 200μg per ml at 70° C, overnight in a humidified chamber. Following stringent washes in SSC buffers, the immunological detection steps were performed at room temperature. The alkaline phosphatase labeled, anti-digoxigenin antibody and detection buffers were purchased from Boehringer Mannheim. The sections were treated with a blocking buffer for one hour and incubated with antibody solution at a 1:5000 dilution for 2 hours, both at room temperature. Colored precipitate was formed by exposure to the alkaline phosphatase substrate nitrobluetetrazoliumchloride/ bromo-chloroindlylphosphate.

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

scholarly journals Lithium-mediated Ferration of Fluoroarenes

2020 ◽  
Vol 74 (11) ◽  
pp. 866-870
Author(s):  
Lewis C. H. Maddock ◽  
Alan Kennedy ◽  
Eva Hevia
Keyword(s):  
Hydrogen Atom ◽  
Organometallic Chemistry ◽  
Room Temperature ◽  
Structural Elucidation ◽  
Side Reactions ◽  
Metal Base ◽  
Lithium Amide ◽  
Mixed Metal ◽  
Important Challenge

While fluoroaryl fragments are ubiquitous in many pharmaceuticals, the deprotonation of fluoroarenes using organolithium bases constitutes an important challenge in polar organometallic chemistry. This has been widely attributed to the low stability of the in situ generated aryl lithium intermediates that even at –78 °C can undergo unwanted side reactions. Herein, pairing lithium amide LiHMDS (HMDS = N{SiMe3}2) with FeII(HMDS)2 enables the selective deprotonation at room temperature of pentafluorobenzene and 1,3,5-trifluorobenzene via the mixed-metal base [(dioxane)LiFe(HMDS)3] (1) (dioxane = 1,4-dioxane). Structural elucidation of the organometallic intermediates [(dioxane)Li(HMDS)2Fe(ArF)] (ArF = C6F5, 2; 1,3,5-F3-C6H2, 3) prior electrophilic interception demonstrates that these deprotonations are actually ferrations, with Fe occupying the position previously filled by a hydrogen atom. Notwithstanding, the presence of lithium is essential for the reactions to take place as Fe II (HMDS)2 on its own is completely inert towards the metallation of these substrates. Interestingly 2 and 3 are thermally stable and they do not undergo benzyne formation via LiF elimination.

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