Silver salts and DBU cooperatively catalyzed domino reaction of propargylic alcohols with trifluoromethyl ketones: direct method to trifluoromethyl-substituted 5-alkylidene-1,3-dioxolane derivatives

2016 ◽  
Vol 31 (1) ◽  
pp. e3545 ◽  
Author(s):  
Jingjing Wang ◽  
Feng Li ◽  
Huanping Xie ◽  
Mengmeng Xu ◽  
Xiaobo Zhao ◽  
...  
Keyword(s):  
Direct Method ◽  
Domino Reaction ◽  
Propargylic Alcohols ◽  
Trifluoromethyl Ketones ◽  
Silver Salts

ChemInform Abstract: Silver Salts and DBU Cooperatively Catalyzed Nucleophilic Addition/Cyclization of Propargylic Alcohols with Trifluoromethyl Ketones.

ChemInform ◽  
2015 ◽  
Vol 46 (36) ◽  
pp. no-no
Author(s):  
Jingjing Wang ◽  
Wei-Guang Kong ◽  
Feng Li ◽  
Jie Liu ◽  
Qin Shen ◽  
...  
Keyword(s):  
Nucleophilic Addition ◽  
Propargylic Alcohols ◽  
Trifluoromethyl Ketones ◽  
Silver Salts

Silver salts and DBU cooperatively catalyzed nucleophilic addition/cyclization of propargylic alcohols with trifluoromethyl ketones

2015 ◽  
Vol 13 (19) ◽  
pp. 5399-5406 ◽  
Author(s):  
Jingjing Wang ◽  
Wei-Guang Kong ◽  
Feng Li ◽  
Jie Liu ◽  
Qin Shen ◽  
...  
Keyword(s):  
Nucleophilic Addition ◽  
Silver Salt ◽  
Efficient Synthesis ◽  
Propargylic Alcohols ◽  
Trifluoromethyl Ketones ◽  
Silver Salts

A general and efficient synthesis of trifluoromethyl substituted 5-alkylidene-1,3-dioxolane using a silver salt and DBU cooperatively catalyzed nucleophilic addition/cyclization of propargylic alcohols and trifluoromethyl ketones is described.

Indium(iii) chloride catalyzed highly diastereoselective domino synthesis of indenodithiepines and indenodithiocines

2015 ◽  
Vol 51 (4) ◽  
pp. 707-710 ◽  
Author(s):  
Sengodagounder Muthusamy ◽  
Manickasamy Sivaguru ◽  
Eringathodi Suresh
Keyword(s):  
Domino Reaction ◽  
Diastereoselective Synthesis ◽  
Propargylic Alcohols

An atom-economical diastereoselective synthesis of indenodithiepines and indenodithiocines has been developed via a domino reaction of propargylic alcohols and dithioacetals in the presence of InCl3 as a catalyst.

Characterization of frozen hydrated biological specimens by low-loss EELS

1992 ◽  
Vol 50 (2) ◽  
pp. 1572-1573
Author(s):  
Songquan Sun ◽  
Richard D. Leapman
Keyword(s):  
Water Content ◽  
Direct Method ◽  
Internal Standard ◽  
Dry Weight ◽  
Dark Field ◽  
Protein Solutions ◽  
Subcellular Compartment ◽  
Differential Shrinkage ◽  
Electron Energy Loss

Analyses of ultrathin cryosections are generally performed after freeze-drying because the presence of water renders the specimens highly susceptible to radiation damage. The water content of a subcellular compartment is an important quantity that must be known, for example, to convert the dry weight concentrations of ions to the physiologically more relevant molar concentrations. Water content can be determined indirectly from dark-field mass measurements provided that there is no differential shrinkage between compartments and that there exists a suitable internal standard. The potential advantage of a more direct method for measuring water has led us to explore the use of electron energy loss spectroscopy (EELS) for characterizing biological specimens in their frozen hydrated state.We have obtained preliminary EELS measurements from pure amorphous ice and from cryosectioned frozen protein solutions. The specimens were cryotransfered into a VG-HB501 field-emission STEM equipped with a 666 Gatan parallel-detection spectrometer and analyzed at approximately −160 C.

A Simple Real-Space Channelling Theory for Electron Diffraction and HREM

1990 ◽  
Vol 48 (1) ◽  
pp. 64-65
Author(s):  
D. Van Dyck
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Direct Method ◽  
Real Space ◽  
Zone Axis ◽  
Phase Object ◽  
High Resolution Images ◽  
The Many ◽  
Analytical Expressions ◽  
Electron Wavefunction

The computation of the many beam dynamical electron diffraction amplitudes or high resolution images can only be done numerically by using rather sophisticated computer programs so that the physical insight in the diffraction progress is often lost. Furthermore, it is not likely that in this way the inverse problem can be solved exactly, i.e. to reconstruct the structure of the object from the knowledge of the wavefunction at its exit face, as is needed for a direct method [1]. For this purpose, analytical expressions for the electron wavefunction in real or reciprocal space are much more useful. However, the analytical expressions available at present are relatively poor approximations of the dynamical scattering which are only valid either for thin objects ((weak) phase object approximation, thick phase object approximation, kinematical theory) or when the number of beams is very limited (2 or 3). Both requirements are usually invalid for HREM of crystals. There is a need for an analytical expression of the dynamical electron wavefunction which applies for many beam diffraction in thicker crystals. It is well known that, when a crystal is viewed along a zone axis, i.e. parallel to the atom columns, the high resolution images often show a one-to-one correspondence with the configuration of columns provided the distance between the columns is large enough and the resolution of the instrument is sufficient. This is for instance the case in ordered alloys with a column structure [2,3]. From this, it can be suggested that, for a crystal viewed along a zone axis with sufficient separation between the columns, the wave function at the exit face does mainly depend on the projected structure, i.e. on the type of atom columns. Hence, the classical picture of electrons traversing the crystal as plane-like waves in the directions of the Bragg beams which historically stems from the X-ray diffraction picture, is in fact misleading.

Remote C(sp3)–H vinylation via radical-mediated consecutive fission of C–H and C–C bonds

2020 ◽  
Vol 7 (19) ◽  
pp. 2981-2985
Author(s):  
Tao Niu ◽  
Shan Yang ◽  
Xinxin Wu ◽  
Chen Zhu
Keyword(s):  
Propargylic Alcohols

Described herein is a radical-mediated vinylation of the remote C(sp3)–H bonds of propargylic alcohols.

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