Are the known ?2-cephems inactive as antibiotics because of an unfavourable steric orientation of their 4?-carboxylic group? Synthesis and biology of two ?2-cephem-4?-carboxylic acids

1987 ◽  
Vol 70 (7) ◽  
pp. 1967-1979 ◽  
Author(s):  
Nissim C. Cohen ◽  
Ivan Ernest ◽  
Riccardo Scartazzini ◽  
Peter Wirz ◽  
Hans Fritz ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Carboxylic Group ◽  
Steric Orientation

scholarly journals Beckmann Rearrangement of 3-carboxybicyclo[3.3.1]nonane and [3.2.1]octane Oximes

2017 ◽  
Vol 5 (2) ◽  
pp. 121-127
Author(s):  
Marian Gorichko ◽  
Andriy Bulochnikov ◽  
Olga Ryzhenko
Keyword(s):  
Carboxylic Acids ◽  
Good Yield ◽  
Beckmann Rearrangement ◽  
Carboxylic Group ◽  
Bicyclic Compounds ◽  
Selective Formation

Regiospecific Beckmann rearrangement of substituted 2-hydroximinonorbornanone carboxylic acids has been investigated. Selective formation of new functionalized 10-oxo-9-azabicyclo[3.3.2]decanes and 7-oxo-6-azabicyclo[3.2.2]nonanes in good yield has been demonstrated. Presence of neighboring carboxylic group allows conducting of Beckmann rearrangement of strained bicyclic compounds.

Action des métaux sur les esters carboxyliques en présence d'hexaméthylphosphortriamide: une méthode simple et efficace de réduction des alcools en alcanes

1984 ◽  
Vol 62 (10) ◽  
pp. 2063-2072 ◽  
Author(s):  
Henri Deshayes ◽  
Jean-Pierre Pete
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Steric Hindrance ◽  
Radical Anion ◽  
Carboxylic Group ◽  
Hexamethylphosphoric Triamide ◽  
Nucleophilic Reactions ◽  
Tert Butanol ◽  
Carboxylic Esters

Carboxylic acids, alcohols (R′OH), and alkanes (R′H) are the main products of the reduction of carboxylic esters (RCO2R′) by sodium in hexamethylphosphoric triamide (HMPA). Alkanes are preferentially formed from the carboxylic esters of hindered alcohols. The alkane content, however, is lowered when there is less steric hindrance on the carboxylic group, and increased when tert-butanol is introduced into the reaction mixture. The reduction of esters in HMPA has been compared to the reduction in alkylamines. The alkane is produced mainly by the decomposition of a radical anion intermediate which can be solvated by HMPA. The alcohol is the result of several possible bimolecular nucleophilic reactions; however, unimolecular and bimolecular processes are involved in the production of the carboxylic acid.

Acidity in water (pKa values) of carboxylic acids derived from simple heterocycles (azoles and azines)

1990 ◽  
Vol 55 (1) ◽  
pp. 72-79 ◽  
Author(s):  
Carlos Cativiela ◽  
Jean-Louis Dejardin ◽  
José Elguero ◽  
José I. Garcia ◽  
Emmanuel Gonzalez ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Theoretical Calculations ◽  
Additive Models ◽  
Carboxylic Group ◽  
Pka Values

The pKa of eighteen heterocyclic carboxylic acids derived from thiophene, furan, pyrrole, benzothiophene, benzofuran, indole, pyridine and quinoline have been determined by spectrophotometry and potentiometry. The values thus obtained are discussed using additive models of the Free-Wilson type. Some theoretical calculations within the AM1 approximation have been carried out in order to understand why annelation effects are dependent on the position, α or β, of the carboxylic group. In the case of pyridine and quinoline carboxylic acids, the problem of tautomerism between neutral and zwitterionic forms has been considered.

Rhodium(III)-catalyzed Intramolecular Ar–H/Ar–H Coupling Directed by Carboxylic Group to Produce Dibenzofuran Carboxylic Acids

2015 ◽  
Vol 44 (11) ◽  
pp. 1598-1600 ◽  
Author(s):  
Takeshi Okada ◽  
Yuto Unoh ◽  
Tetsuya Satoh ◽  
Masahiro Miura
Keyword(s):  
Carboxylic Acids ◽  
Carboxylic Group

A convenient preparative method for 1,4-diketones from carboxylic acids

1977 ◽  
Vol 27 (1) ◽  
pp. 117-120
Author(s):  
Shoji Watanabe ◽  
Tsutomu Fujita ◽  
Kyoichi Suga ◽  
Haruhiko Abe
Keyword(s):  
Carboxylic Acids ◽  
Preparative Method

Probing The Resolution of 2-Alkoxy and 2-Aryloxy Carboxylic Acids

2006 ◽  
Author(s):  
Jason Eames ◽  
Ewan Boyd ◽  
Sameer Chavda
Keyword(s):  
Carboxylic Acids
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