Enantioselective Hydrophosphonylation of N-Boc Imines using Chiral Guanidine–Thiourea Catalysts

The synthesis of a new family of pentacoordinated spiro[4,4]phosphoranes stabilized by the ortho-benzamide bidentate ligand (oBA,-C6H4-2-C(O)NH-) through reaction of Cα -Cortho-dilithiated phosphazenes with oxiranes is reported. Mixtures of epimers that differ in configuration at the phosphorus atom were obtained with moderate to high yields and diastereoselectivities. C3-disubstituted derivatives could be separated, which provided access to enantiopure products arising from the reaction with (R)-2-phenyloxirane. Stereomutation was observed by heating the spirophosphoranes at 100 ºC. Directed ortho lithiation of spirophoshoranes followed by electrophilic quench reactions including carbon-based and heteroatom-based electrophiles afforded derivatives functionalized in remote position with respect to the phosphorus atom. Benzoic acid catalyzed hydrolysis of spirophosphoranes furnished ortho-(hydroxyalkylphosphoryl)benzamides by cleavage of the P‒O and P‒N bonds with retention of the phosphorus configuration. In contrast, alkaline hydrolysis led to the formation of γ-hydroxyphosphinic acids and benzamide.

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Efficient Synthesis of a New Family of 2,6-Disulfanyl-9-Selenabicyclo[3.3.1]Nonanes

Molecules ◽

10.3390/molecules26102849 ◽

2021 ◽

Vol 26 (10) ◽

pp. 2849

Author(s):

Maxim V. Musalov ◽

Vladimir A. Potapov ◽

Svetlana V. Amosova

Keyword(s):

Nucleophilic Substitution ◽

Nucleophilic Addition ◽

Triple Bond ◽

Efficient Synthesis ◽

New Family ◽

Stereoselective Addition ◽

Benzyl Halides ◽

High Yields ◽

Derivatives Of ◽

Alkyl Propiolates

The efficient synthesis of a new family of 2,6-disulfanyl-9-selenabicyclo[3.3.1]nonanes in high yields has been developed based on 9-selenabicyclo[3.3.1]nonane-2,6-dithiolate anion generated from bis-isothiouronium salt of 2,6-dibromo-9-selenabicyclo[3.3.1]nonane. The derivatives of 2,6-disulfanyl-9-selenabicyclo[3.3.1]nonane containing alkyl, allyl and benzyl moieties have been prepared in 90–99% yields by nucleophilic substitution of 9-selenabicyclo[3.3.1]nonane-2,6-dithiolate anion with alkyl, allyl and benzyl halides. The reaction of nucleophilic addition of 9-selenabicyclo[3.3.1]nonane-2,6-dithiolate anion to alkyl propiolates afforded 2,6-di(vinylsulfanyl)-9-selenabicyclo[3.3.1]nonanes. The conditions for regio- and stereoselective addition of 9-selenabicyclo[3.3.1]nonane-2,6-dithiolate anion to a triple bond of alkyl propiolates have been found. To date, not a single representative of 2,6-disulfanyl-9-selenabicyclo[3.3.1]nonanes has been described in the literature.

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Catalyst-Free Three-Component Synthesis of Spirobenzimidazolidines Bearing an Indole Scaffold

Synlett ◽

10.1055/s-0037-1609950 ◽

2018 ◽

Vol 29 (17) ◽

pp. 2301-2305 ◽

Cited By ~ 3

Author(s):

F. Moghaddam ◽

A. Moafi ◽

Z. Zamani ◽

M. Daneshfar

Keyword(s):

Reaction Times ◽

Reaction Conditions ◽

One Pot ◽

Efficient Catalyst ◽

Catalyst Free ◽

New Family ◽

Three Component Reaction ◽

High Yields ◽

First Time ◽

Derivatives Of

An efficient catalyst-free one-pot three-component reaction was developed for the synthesis of a new family of N- and S-containing spirocyclic compounds. Various derivatives of spirobenzimidazolidine containing an indole scaffold were synthesized for the first time in a modestly toxic solvent and under mild reaction conditions. The reaction times were of the order of several minutes, and all the products were obtained in moderate to high yields (overall yields 58–80%).

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Uncatalysed Preparation of α-Amino Phosphonates under Solvent Free Conditions

Journal of Chemical Research ◽

10.3184/0308234054323887 ◽

2005 ◽

Vol 2005 (5) ◽

pp. 324-327 ◽

Cited By ~ 12

Author(s):

Mohamed Zahouily ◽

Abdelhakim Elmakssoudi ◽

Abdessamad Mezdar ◽

Ahmed Rayadh ◽

Saïd Sebti

Keyword(s):

Microwave Irradiation ◽

Carbonyl Compounds ◽

Environmentally Friendly ◽

Solvent Free ◽

Aliphatic Amines ◽

Solvent Free Conditions ◽

Dialkyl Phosphites ◽

High Yields ◽

Amino Phosphonates ◽

Aromatic And Aliphatic Amines

A simple, efficient and environmentally friendly procedure has been developed for the three component coupling of carbonyl compounds, aromatic and aliphatic amines and dialkyl phosphites to produce α-amino phosphonates. The α-amino phosphonates are synthesised in high yields (74–97%) in a few minutes (1–3 min) by microwave irradiation under solvent-free conditions, avoiding the use of any catalyst.

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The N-Terminal Domain of OmpATb Is Required for Membrane Translocation and Pore-Forming Activity in Mycobacteria

Journal of Bacteriology ◽

10.1128/jb.00509-07 ◽

2007 ◽

Vol 189 (17) ◽

pp. 6351-6358 ◽

Cited By ~ 23

Author(s):

Anuradha Alahari ◽

Nathalie Saint ◽

Sylvie Campagna ◽

Virginie Molle ◽

Gérard Molle ◽

...

Keyword(s):

Cell Wall ◽

Lipid Bilayers ◽

Single Channel ◽

Chimeric Protein ◽

E Coli ◽

Terminal Domain ◽

New Family ◽

High Yields ◽

Mycobacterial Cell Wall ◽

First Time

ABSTRACT OmpATb is the prototype of a new family of porins in Mycobacterium tuberculosis and Mycobacterium bovis BCG. Although the pore-forming activity of this protein has been clearly established by using recombinant protein produced in Escherichia coli, characterization of the native porin has been hampered by the scarce amount of protein present in the M. tuberculosis detergent extracts. To this aim, we have developed a protocol to overproduce and obtain high yields of OmpATb in both Mycobacterium smegmatis and M. bovis BCG. The protein could be extracted and purified from the cell wall fraction and subsequently used for analysis of the pore-forming activity in multichannel and single-channel conductance experiments. Our results indicate that OmpATb produced in mycobacteria presents an average conductance value of 1,600 ± 100 pS, slightly higher than that of OmpATb produced in E. coli, suggesting the occurrence of OmpATb in a highly ordered organization within the mycobacterial cell wall. In contrast to OmpATb, a truncated form lacking the first 72 amino acids (OmpATb73-326) was essentially found in the cytosol and was not active in planar lipid bilayers. This suggested that the N-terminal domain of OmpATb could participate in targeting of OmpATb to the cell wall. This was further confirmed by analyzing M. smegmatis clones expressing a chimeric protein consisting of a fusion between the N-terminal domain of OmpATb and the E. coli PhoA reporter. The present study shows for the first time that the N terminus of OmpATb is required for targeting the porin to the cell wall and also appears to be essential for its pore-forming activity.

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Microstructure and crystal symmetry of Pb2Sr2(Y/Ca)Cu3O9−δ

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100173455 ◽

1990 ◽

Vol 48 (4) ◽

pp. 64-65

Author(s):

Y. P. Lin ◽

J. S. Xue ◽

J. E. Greedan

Keyword(s):

Electron Diffraction ◽

High Temperature Superconductors ◽

Carbon Film ◽

Basic Structure ◽

Crystal Symmetry ◽

X Ray Diffraction ◽

X Ray ◽

Space Groups ◽

New Family ◽

Convergent Beam

A new family of high temperature superconductors based on Pb2Sr2YCu3O9−δ has recently been reported. One method of improving Tc has been to replace Y partially with Ca. Although the basic structure of this type of superconductors is known, the detailed structure is still unclear, and various space groups has been proposed. In our work, crystals of Pb2Sr2YCu3O9−δ with dimensions up to 1 × 1 × 0.25.mm and with Tc of 84 K have been grown and their superconducting properties described. The defects and crystal symmetry have been investigated using electron microscopy performed on crushed crystals supported on a holey carbon film.Electron diffraction confirmed x-ray diffraction results which showed that the crystals are primitive orthorhombic with a=0.5383, b=0.5423 and c=1.5765 nm. Convergent Beam Electron Diffraction (CBED) patterns for the and axes are shown in Figs. 1 and 2 respectively.

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A new family of fluorescent calcium indicators designed to resist leakage or for measuring calcium near membranes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168578 ◽

1994 ◽

Vol 52 ◽

pp. 168-169

Author(s):

Martin Poenie ◽

Akwasi Minta ◽

Charles Vorndran

Keyword(s):

Metal Binding ◽

Acetoxymethyl Ester ◽

Binding Properties ◽

Fura 2 ◽

New Family ◽

Anion Transporter ◽

Calcium Indicator ◽

Calcium Indicators ◽

High Calcium ◽

Intracellular Compartmentalization

The use of fura-2 as an intracellular calcium indicator is complicated by problems of rapid dye leakage and intracellular compartmentalization which is due to a probenecid sensitive anion transporter. In addition there is increasing evidence for localized microdomains of high calcium signals which may not be faithfully reported by fura-2.We have developed a new family of fura-2 analogs aimed at addressing some of these problems. These new indicators are based on a modified bapta which can be readily derivatized to produce fura-2 analogs with a variety of new properties. The modifications do not affect the chromophore and have little impact on the spectral and metal binding properties of the indicator. One of these new derivatives known as FPE3 is a zwitterionic analog of fura-2 that can be loaded into cells as an acetoxymethyl ester and whose retention in cells is much improved. The improved retention of FPE3 is important for both cuvettebased measurements of cell suspensions and for calcium imaging.

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Scanning tunneling microscopy and atomic force microscopy: New tools for biology

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100155864 ◽

1989 ◽

Vol 47 ◽

pp. 778-779

Author(s):

CE Bracker ◽

P. K. Hansma

Keyword(s):

Physical Property ◽

Scanning Probe ◽

Scanning Tunneling ◽

Small Scale ◽

Tunneling Microscopy ◽

Force Microscopy ◽

New Family ◽

Small Probe ◽

Atomic Force ◽

Transmission Electron

A new family of scanning probe microscopes has emerged that is opening new horizons for investigating the fine structure of matter. The earliest and best known of these instruments is the scanning tunneling microscope (STM). First published in 1982, the STM earned the 1986 Nobel Prize in Physics for two of its inventors, G. Binnig and H. Rohrer. They shared the prize with E. Ruska for his work that had led to the development of the transmission electron microscope half a century earlier. It seems appropriate that the award embodied this particular blend of the old and the new because it demonstrated to the world a long overdue respect for the enormous contributions electron microscopy has made to the understanding of matter, and at the same time it signalled the dawn of a new age in microscopy. What we are seeing is a revolution in microscopy and a redefinition of the concept of a microscope.Several kinds of scanning probe microscopes now exist, and the number is increasing. What they share in common is a small probe that is scanned over the surface of a specimen and measures a physical property on a very small scale, at or near the surface. Scanning probes can measure temperature, magnetic fields, tunneling currents, voltage, force, and ion currents, among others.

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Porphyrin-functionalized coordination star polymers and their potential applications in photodynamic therapy

Polymer Chemistry ◽

10.1039/c9py01391a ◽

2019 ◽

Vol 10 (45) ◽

pp. 6116-6121 ◽

Cited By ~ 3

Author(s):

Tan Ji ◽

Lei Xia ◽

Wei Zheng ◽

Guang-Qiang Yin ◽

Tao Yue ◽

...

Keyword(s):

Photodynamic Therapy ◽

Self Assembly ◽

Star Polymers ◽

New Family ◽

Potential Applications

We present a new family of porphyrin-functionalized coordination star polymers prepared through combination of coordination-driven self-assembly and post-assembly polymerization. Their self-assembly behaviour in water and potential for photodynamic therapy were demonstrated.

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A Look at Work and the New Family

Contemporary Psychology ◽

10.1037/023873 ◽

1985 ◽

Vol 30 (6) ◽

pp. 497-498

Author(s):

Carol C. Nadelson

Keyword(s):

New Family

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