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Suprofen, which is produced from thiophene-2-carboxylic acid, is the active ingredient in some eye drops. [2] Upon treatment with LDA, thiophene-2-carboxylic acid undergoes double deprotonation to give the 5-lithio derivative, a precursor to many 5-substituted derivatives. [3] Thiophene-2-carboxylic acid has been widely studied as a substrate ...
The Fiesselmann thiophene synthesis is a name reaction in organic chemistry that allows for the generation of 3-hydroxy-2-thiophenecarboxylic acid derivatives from α,β-acetylenic esters with thioglycolic acid and its derivatives under the presence of a base. The reaction was developed by Hans Fiesselmann in the 1950s.
At neutral pH, thiocarboxylic acids are fully ionized. Thiocarboxylic acids are about 100 times more acidic than the analogous carboxylic acids. Thiobenzoic acid has a pK a of 2.48 compared with 4.20 for benzoic acid, and thioacetic acid has a pK a near 3.4 compared with 4.72 for acetic acid. [8]
Thiophene-2-carboxaldehyde is an organosulfur compound with the formula C 4 H 3 SCHO. It is one of two isomeric thiophenecarboxaldehydes. It is a colorless liquid that often appears amber after storage. It is versatile precursor to many drugs including eprosartan, Azosemide, and Teniposide.
The reaction of boron trichloride with alcohols was reported in 1931, and was used to prepare dimethoxyboron chloride, B(OCH 3) 2 Cl. [3] Egon Wiberg and Wilhelm Ruschmann used it to prepare tetrahydroxydiboron by first introducing the boron–boron bond by reduction with sodium and then hydrolysing the resulting tetramethoxydiboron, B 2 (OCH 3) 4, to produce what they termed sub-boric acid. [4]
Removal of the BOC group in amino acids can be accomplished with strong acids such as trifluoroacetic acid in dichloromethane, or with HCl in methanol. [2] [3] [4] A complication may be the tendency of the t-butyl cation intermediate to alkylate other nucleophiles; scavengers such as anisole or thioanisole may be used.
While polyunsaturated fatty acids are unusual in plant cuticles, a diunsaturated dicarboxylic acid has been reported as a component of the surface waxes or polyesters of some plant species. Thus, octadeca-c6,c9-diene-1,18-dioate, a derivative of linoleic acid , is present in Arabidopsis and Brassica napus cuticle.
[2] The complex can reduce carboxylic acids to alcohols and is a common route for the reduction of amino acids to amino alcohols [3] (e.g. valinol). It adds across alkenes to give organoboron compounds that are useful intermediates. [4]