Decarboxylation derivatives

Biogenic amines are decarboxylated derivatives of tyrosine and tryptophan that are found in animals from simple invertebrates to mammals. These compounds are found in neural tissue, where they function as neurotransmitters, and in non-neural tissues, where they have a variety of functions. The enzymes involved in biogenic amine synthesis and many receptors for these compounds have been isolated from both invertebrate and vertebrate sources. In all cases, the individual proteins that effect biogenic amine metabolism and function show striking similarity between species, indicating that these are ancient and well-conserved pathways. 

Heating of the pyrazolinyl-5-carboxylates 156 in dilute HC1 generated the bispyazolylpyrazines 157 (Equation 37). Prolonged heating yielded the decarboxylated derivatives <1997RRC1141, 1997PHA101>. 

The antibacterial, nalidixic acid (337), is associated with a high incidence of photosensitivity reactions. Detzer and Huber irradiated a solution in 0.1 M sodium hydroxide with a high-pressure mercury lamp and identified four photodegradation products the decarboxylated derivative (338), carbon dioxide, ethylamine, and the new dione (339) [188]. 

The reaction of 2-aminothiophene-3-carboxylic acids (55) or 2-aminotet-rahydrobenzo(b)thiophene-3-carboxylic acid [55, R = R1 = —(CH2)4—] and EMME by heating at 110-120°C for 1-2 hr gave a mixture of 3-carboxylic acids (56) and decarboxylated derivatives (57) (75GEP2435025). 

Mebendazole is given orally it is poorly soluble, and very little is absorbed from the intestinal tract. About 5 to 10%, principally the decarboxylated derivatives, is recovered in the urine most of the orally administered drug is found in the feces within 24 hours. 

Less than 10% of orally administered mebendazole is absorbed. The absorbed drug is protein-bound (> 90%), is rapidly converted to inactive metabolites (primarily during its first pass in the liver), and has a half-life of 2-6 hours. It is excreted mostly in the urine, principally as decarboxylated derivatives. In addition, a portion of absorbed drug and its derivatives are excreted in the bile. Absorption is increased if the drug is ingested with a fatty meal. 

Confirmation of the identity of the suspected liquid chromatographic peaks in quinolone analysis can be made by converting the analytes to the corresponding decarboxylated derivatives and analyzing them by gas chromatography-mass spectrometry (195, 196). Most promising screening and even confirmatory methods in terms of simplicity, selectivity, and sensitivity, are those described by Munns et al. (196), Roybal et al. (188), and Eng et al. (193). 

Assmann et al. described, in addition to known alkaloids, the isolation of the first pyrrole-imidazole alkaloid with a guanidine function instead of the aminoimidazole (127) [152] from the sponge Agdas wiedenmayeri, while its decarboxylated derivate laughine (128) was isolated from the sponge Eurypon laughlini [153],... 

Polyfluoroalk-2-ynoic acids 7 readily undergo an intermolecular-intrarnolecular Michael addition reaction with a variety of bifunctional azanucleophiles and o-phenylenediamine. to give the corresponding carboxylated and/or decarboxylated 2-(polyfluoroalkyl)imidazolidine (e. g, 8 and 9. respectively), thiazolidine, and oxazolidine derivatives in moderate to good yields. The products formed depend strongly on the reaction conditions employed. For example, the decarboxylated derivative 9 is only formed under reflux conditions. ... 

In the presence of malate deshydrogenase (MDH), oxaloacetate and pyruvate, its decarboxylation derivative, are reduced to L-malate by reduced NADH. The equilibrium of the reaction is forced in the direction of the products by the judicious selection of operating conditions (buffer pH7.8 and an excess of NADH) ... 

Hydroxybenzoic and hydroxycinnamic acids are characterized by relatively high flavor thresholds (> ppm, mainly bitter taste and astringency) [82]. On the other hand, their decarboxylated derivatives (Fig. 75.5) can impart very strong phenolic/ clove/smoked flavors to beer because of their low threshold values (ppb order). 

---