Crown ether catalysis of decarboxylation and decarbalkoxylation of β-keto acids and malonates: a synthetic application

1980 ◽  
Vol 58 (21) ◽  
pp. 2271-2277 ◽  
Author(s):  
Duncan H. Hunter ◽  
Vijay Patel ◽  
Richard A. Perry
Keyword(s):  
Crown Ether ◽  
Remarkable Difference ◽  
Potassium Salts ◽  
One Pot ◽  
Keto Esters ◽  
Step Procedure ◽  
Keto Acids ◽  
Synthetic Application ◽  
Sodium And Potassium

The effect of 18-crown-6 ether on the decarboxylation rates of the sodium and potassium salts of 3-camphorcarboxylic acid 1 and of 1-carbomethoxy-1-carboxycyclohexane 2 was studied. For 2 the K-18C6 salt reacted ca. 104 times faster than the parent acid. This remarkable difference in reactivity was used in developing a one-pot, two-step procedure for decarbalkoxylation of malonic esters. This procedure was then applied to a range of malonates, β-keto esters, and an α-cyano ester. The effect of 15C5, other cations, and good nucleophiles was also studied.

Synthesis of Sulfoquinovose and Sulfoquinovosyl Diacylglycerides, and a Fluorogenic Substrate for Sulfoquinovosidases

2019 ◽  
Author(s):  
Yunyang Zhang ◽  
Janice Mui ◽  
Thimali Arumaperuma ◽  
James P. Lingford ◽  
ETHAN GODDARD-BORGER ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Fluorogenic Substrate ◽  
Potassium Salts ◽  
X Ray ◽  
Sulfoquinovosyl Diacylglycerol ◽  
Sodium And Potassium

<p>The sulfolipid sulfoquinovosyl diacylglycerol (SQDG) and its headgroup, the sulfosugar sulfoquinovose (SQ), are estimated to harbour up to half of all organosulfur in the biosphere. SQ is liberated from SQDG and related glycosides by the action of sulfoquinovosidases (SQases). We report a 10-step synthesis of SQDG that we apply to the preparation of saturated and unsaturated lipoforms. We also report an expeditious synthesis of SQ and (<sup>13</sup>C<sub>6</sub>)SQ, and X-ray crystal structures of sodium and potassium salts of SQ. Finally, we report the synthesis of a fluorogenic SQase substrate, methylumbelliferyl a-D-sulfoquinovoside, and examination of its cleavage kinetics by two recombinant SQases.</p>

Heats of Solution of Some Sodium and Potassium Salts in Water and in Water-Methanol Mixtures

1992 ◽  
Vol 57 (11) ◽  
pp. 2227-2234 ◽  
Author(s):  
Ján Benko ◽  
Oľga Vollárová
Keyword(s):  
Transfer Functions ◽  
Enthalpies Of Solution ◽  
Potassium Salts ◽  
Solvent Interactions ◽  
Heats Of Solution ◽  
Solvent Molecules ◽  
Sodium And Potassium

The enthalpies of solution ∆Hs0 were determined for NaSCN, KSCN, NaBrO3, KBrO3, NaClO3, KClO3, NaIO4, KMnO4, KNO2 and NaNO2 in water-methanol mixtures. The transfer functions ∆Ht0 of the salts and anions were calculated based on the extrathermodynamic TPTB assumption. The ∆Ht0 values of the anion obtained from the sodium and potassium salts were compared. The differences observed, particularly at higher concentrations of the cosolvent, are discussed with respect to the interactions between the solvent molecules and the solute-solvent interactions.

scholarly journals 2-Aryl-6-Polyfluoroalkyl-4-Pyrones as Promising RF-Building-Blocks: Synthesis and Application for Construction of Fluorinated Azaheterocycles

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4415
Author(s):  
Sergey A. Usachev ◽  
Diana I. Nigamatova ◽  
Daria K. Mysik ◽  
Nikita A. Naumov ◽  
Dmitrii L. Obydennov ◽  
...  
Keyword(s):  
Direct Synthesis ◽  
Building Blocks ◽  
Oxidative Cyclization ◽  
One Pot ◽  
Synthetic Application ◽  
General Method

A convenient and general method for the direct synthesis of 2-aryl-6-(trifluoromethyl)-4-pyrones and 2-aryl-5-bromo-6-(trifluoromethyl)-4-pyrones has been developed on the basis of one-pot oxidative cyclization of (E)-6-aryl-1,1,1-trifluorohex-5-ene-2,4-diones via a bromination/dehydrobromination approach. This strategy was also applied for the preparation of 2-phenyl-6-polyfluoroalkyl-4-pyrones and their 5-bromo derivatives. Conditions of chemoselective enediones bromination were found and the key intermediates of the cyclization of bromo-derivatives to 4-pyrones were characterized. Synthetic application of the prepared 4-pyrones has been demonstrated for the construction of biologically important CF3-bearing azaheterocycles, such as pyrazoles, pyridones, and triazoles.

Self-assembly of sodium and potassium betulinates into hydro- and organo-gels: entrapment and removal studies of fluorophores and synthesis of gel–gold nanoparticle hybrid materials

RSC Advances ◽  
2016 ◽  
Vol 6 (21) ◽  
pp. 17290-17296 ◽  
Author(s):  
Braja Gopal Bag ◽  
Shib Shankar Dash
Keyword(s):  
Gold Nanoparticle ◽  
Hybrid Materials ◽  
Betulinic Acid ◽  
Self Assembly ◽  
Solvent Mixtures ◽  
Potassium Salts ◽  
Aqueous Solvent Mixtures ◽  
Aqueous Solvent ◽  
Removal Studies ◽  
Sodium And Potassium

Sodium and potassium salts of a renewable nano-sized triterpenoid betulinic acid have been prepared and their self-assembly properties in water and aqueous solvent mixtures have been studied.

Short protecting-group-free synthesis of 5-acetylsulfanyl-histidines in water: novel precursors of 5-sulfanyl-histidine and its analogues

2016 ◽  
Vol 14 (44) ◽  
pp. 10473-10480 ◽  
Author(s):  
Sylvain Daunay ◽  
Remi Lebel ◽  
Laurence Farescour ◽  
Jean-Claude Yadan ◽  
Irene Erdelmeier
Keyword(s):  
Amino Acids ◽  
Protecting Group ◽  
One Pot ◽  
Step Procedure ◽  
Sulfur Containing

Natural and novel sulfur-containing amino acids are preparedviaa new regioselective one-pot two-step procedure.

One-pot efficient synthesis of aryl α-keto esters from aryl-ketones

Tetrahedron ◽  
2009 ◽  
Vol 65 (47) ◽  
pp. 9797-9800 ◽  
Author(s):  
Jing Zhuang ◽  
Changqing Wang ◽  
Fang Xie ◽  
Wanbin Zhang
Keyword(s):  
Efficient Synthesis ◽  
One Pot ◽  
Keto Esters ◽  
Aryl Ketones

scholarly journals Microwave-Assisted Vacuum Synthesis of TiO2 Nanocrystalline Powders in One-Pot, One-Step Procedure

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 149
Author(s):  
Enrico Paradisi ◽  
Roberto Rosa ◽  
Giovanni Baldi ◽  
Valentina Dami ◽  
Andrea Cioni ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Sol Gel ◽  
Reaction Medium ◽  
Process Intensification ◽  
Nanocrystalline Powders ◽  
Fast Heating ◽  
One Pot ◽  
Nanoparticle Suspension ◽  
Step Procedure ◽  
One Step

A new method for fast and simple synthesis of crystalline TiO2 nanoparticles with photocatalytic activity was developed by carrying out a classic sol–gel reaction directly under vacuum. The use of microwaves for fast heating of the reaction medium further reduces synthesis times. When the solvent is completely removed by vacuum, the product is obtained in the form of a powder that can be easily redispersed in water to yield a stable nanoparticle suspension, exhibiting a comparable photocatalytic activity with respect to a commercial product. The present methodology can, therefore, be considered a process intensification procedure for the production of nanotitania.

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