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Pyrimidines
Published in Mihai V. Putz, New Frontiers in Nanochemistry, 2020
Nicoleta A. Dudaş, Mihai V. Putz
Pyrimidine catabolism in plants has not been well characterized, but it appears to function as a reverse of the de novo biosynthetic pathway (Rider, 2009; Kafer et al., 2004). For pyrimidine catabolism in other organisms three pathways are known, two of these more investigated and spread (Rider, 2009; Rider et al., 2009; Kafer et al., 2004). Pyrimidines are ultimately degraded to CO2, H2O, and urea (Rider, 2009; Kafer et al., 2004). The reductive pathway is found in most organisms (Rider, 2009; Kafer et al., 2004). The pyrimidine nucleosides are dephosphorylated, nucleosides are cleaved in ribose 1-phosphate and free pyrimidine bases (Rider, 2009; Kafer et al., 2004). Uracil or thymine undergoes reduction, uracil is broken down to N-carbamoyl-β-alanine which is converted to CO2, NH4+, and β-alanine, while thymine is broken down into CO2, NH4+ and β-aminoisobutyrate, which can be further broken down into intermediates eventually leading into the citric acid cycle (Figure 41.9) (Rider, 2009; Rider et al., 2009; Kafer et al., 2004; Schackerz et al., 2006). The products from the degradation of pyrimidine are excreted into urine or converted into urea (CO2, NH4+, and H2O) (Rider, 2009; Kafer et al., 2004; Schackerz et al., 2006). In some bacteria was found the oxidative pathway of pyrimidine catabolism: pyrimidines are oxidized to barbituric acid which is then broken down into ureidomalonic acid, and finally into urea and malonic acid (Rider, 2009; Kafer et al., 2004; Loh et al., 2006).
Characteristics of Polymers and Polymerization Processes
Published in Manas Chanda, Plastics Technology Handbook, 2017
Within the last two decades, a number of chemical structures have been proposed as metal deactivators for polyolefins. These include carboxylic acid amides of aromatic mono- and di-carboxylic acids and N-substituted derivatives such as N,N′-diphenyloxamide, cyclic amides such as barbituric acid, hydrazones and bishydrazones of aromatic aldehydes such as benzaldehyde and salicylaldehyde or of o-hydroxy-arylketones, hydrazides of aliphatic and aromatic mono- and di-carboxylic acids as well as N-acylated derivatives thereof, bisacylated hydrazine derivatives, polyhydrazides, and phosphorus acid ester of a thiobisphenol.
Catalytic Asymmetric Michael Addition of 1,3-Dicarbonyls to Nitroalkenes
Published in Irishi N. N. Namboothiri, Meeta Bhati, Madhu Ganesh, Basavaprabhu Hosamani, Thekke V. Baiju, Shimi Manchery, Kalisankar Bera, Catalytic Asymmetric Reactions of Conjugated Nitroalkenes, 2020
Irishi N. N. Namboothiri, Meeta Bhati, Madhu Ganesh, Basavaprabhu Hosamani, Thekke V. Baiju, Shimi Manchery, Kalisankar Bera
Rawal et al. described an asymmetric Michael addition of barbituric acid 39 to nitroalkenes 1 to afford the chiral barbiturate derivatives 40 in excellent yields and enantioselectivities by employing 0.05 mol% of newly synthesized thiosquaramide catalyst C63 (Scheme 1.41).113
Synthesis, structural, magnetic and thermal studies of copper(II) 5,5-diethylbarbiturate complexes with nicotinamide, 2,2′-bipyridine and triethanolamine
Published in Journal of Coordination Chemistry, 2023
Veysel T. Yilmaz, Fatih Yilmaz, Ceyda Icsel, Muhittin Aygun
Barbiturates (BAs) derived from barbituric acid (1,3-diazinane-2,4,6-trione) are known to act as central nervous system depressants [1]. They were extensively used as sedative-hypnotic drugs. Barbituric acid does not exhibit medicinal activity, and the pharmacological properties of BAs seem to be modified by the functional groups on the C5 atom of the pyrimidine ring [2]. Approximately 2000 different barbiturate derivatives have been previously prepared and nearly 50 of them displayed sedative/hypnotic activity and used in psychiatry and neurology [3]. Some medical treatments with biologically active BAs are still in use today.