2-Pyrazinecarboxylic acid hydroxylation

An interesting report is the hydroxylation of pyrazinecarboxylic acid 38 with biocatalysts <1994SL814>, where all isomers of hydroxypyrazinecarboxylic acids can be prepared by the use of three individual wild-type microorganisms in whole-cell biotransformations. The enzymatic hydroxylation is most practical for the synthesis of... 

Pyrazinecarboxylic acid underwent microbiological hydroxylation to give 3-oxo-3,4-dihydro- (36, R = H) (Alcaligenes eutrophus 70%), 5-oxo-4, 5-dihydro- (37) (.Pseudomonas acidovorans 96%), or 6-oxo-l,6-dihydro-2-pyrazinecarboxylic acid (38) (Alcaligenes faecalis 85%) 1091 Similar procedures afforded 5-chloro-3-oxo-3,4-dihydro-2-pyrazinecarboxylic acid (Alcaligenes eutrophus 50%) and 5-oxo-4,5-dihydro-2-pyrazinecarbonitrile (Agrobacterium sp 78%).1091... 

Pyrazinecarboxylic acid underwent microbiological hydroxylation to give 3-oxo-3,4-dihydro- (36, R = H) (Alcaligenes eutrophus 70%), 5-oxo-4,... 

A. Kiener, J.-P. Roduit, A. Tschech, A. Tin-schert, K. Heinzmann, Regiospeciflc enzymatic hydroxylations of pyrazinecarboxylic acid and a practical synthesis of 5-chlor-opyrazine-2-carboxylic acid, Synlett 1994, 10, 814-816. 

The Fenton-type system, Fe(II)/Cu(n)/H202, produced phenol with a moderate selectivity [28b]. In the absence of Cu(II) or Fe(III), biphenyl was the main product. Quinones, in particular l,2-naphthoquinone-4-sulfonate, played a vital role in the Fe(III)-promoted hydroxylation of benzene with HjOj, giving moderate yields of phenol [70]. The addition of polyethyleneglycol to Fe(III)/ HjOj in aqueous acetonitrile enhanced the phenol yield and selectivity [71]. A heterophase reaction in the presence of surfactants (quaternary ammonium salts, crown ethers, and polymers) has led to a further improvement. Biphasic benzene hydroxylation in the system composed of aqueous H O, Fe SO modified with 2-pyrazinecarboxylic acid (Hpca) derivatives, and CF COOH produced phenol with a selectivity of 97% (based on benzene) at substrate conversion of 8.6% (Eq. 14.22)... 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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