Heterocyclic compounds derivatives

The importance of the penicillins as a class of heterocyclic compounds derives primarily from their effectiveness in the treatment of bacterial infections in mammals (especially humans). It has been estimated that, in 1980, the worldwide production of antibiotics was 25 000 tons and, of this, approximately 17 000 tons were penicillins (81MI51103). The Food and Drug Administration has estimated that, in 1979 in the U.S.A., 30.1 x 10 prescriptions of penicillin V and 44.3 x 10 prescriptions of ampicillin/amoxicillin were dispensed. This level of usage indicates that, compared to other methods of dealing with bacterial infection, the cost-benefit properties of penicillin therapy are particularly favorable. Stated differently, penicillin treatment leads to the elimination of the pathogen in a relatively high percentage of cases of bacterial infection at a relatively low cost to the patient in terms of toxic reactions and financial resources. 

The bases that occur in nucleic acids are aromatic heterocyclic compounds derived from either pyrimidine or purine. Five of these bases are the main components of nucleic acids in all living creatures. The purine bases adenine (abbreviation Ade, not A ) and guanine (Gua) and the pyrimidine base cytosine (Cyt) are present in both RNA and DNA. In contrast, uracil (Ura) is only found in RNA. In DNA, uracil is replaced by thymine (Thy), the 5-methyl derivative of uracil. 5-methylcyto-sine also occurs in small amounts in the DNA of the higher animals. A large number of other modified bases occur in tRNA (see p. 82) and in other types of RNA. 

In heated foods the main reactions by which flavors are formed are the Maillard reaction and the thermal degradation of lipids. These reactions follow complex pathways and produce reactive intermediates, both volatile and non-volatile. It has been demonstrated that lipids, in particular structural phospholipids, are essential for the characteristic flavor development in cooked meat and that the interaction of lipids with products of the Maillard reaction is an important route to flavor. When model systems containing amino acids and ribose were heated in aqueous buffer, the addition of phospholipids had a significant effect on the aroma and on the volatile products. In addition a number of heterocyclic compounds derived from lipid - Maillard interactions were found. The extent of the interaction depends on the lipid structure, with phospholipids reacting much more readily than triglycerides. 

Heterocyclic Compounds Derived from -Amino- -deoxy-D-glucose... 

Bowden K, Jones ERH (1946) Acetylenic compounds. IX. Heterocyclic compounds derived from ethynyl ketones. J Chem Soc 25 953-954... 

D. Heterocyclic Compounds Derived from Dipeptides or Dipeptidomimetics... 

There are three types of nomenclature used for heterocyclic compounds. Many heterocycles have trivial names, which are based on their occurrence, special properties, or historical reasons such as discovery of particular material. Systematic names of heterocyclic compounds derived from the structure of the compound are governed by lUPAC rules, which are divided into two groups the Hantzsch-Widman and replacement nomenclatures. In this book, we were trying to follow the guidelines for naming the heterocyclic compounds, which are summarized in Chapter 2 of the excellent book The Chemistry of Heterocycles Structures, Reactions, and Applications ... 

S. G. Kucukguzel, I. Kucukguzel, E. Tatar, S. RoUas, F. Sahin, M. GuUuce, E. De Clercq, and L. Kabasakal. Synthesis of some novel heterocyclic compounds derived from diflunisal hydrazide as potential anti-infective and antiinflammatory agents. Eur. J. Med. Chem., 42(7) 893-901, July 2007. 

Covalent phosphorus compounds (sugar phosphates, phytic acid and nucleotides) have already been mentioned several times. Foods also contain many organic sulfur compounds, such as sulfur-containing amino acids, thiols, (oHgo)sulfides, glucosi-nolates, heterocyclic compounds (derivatives of thiophene and thiazole). Their occurrence, properties, reactions and importance are covered elsewhere in this book. 

Tolmachev, A.A., S.I. Dovgopoly, A.N. Kostyuk et al. 1997. Phosphorus-containing heterocyclic compounds derived from N-vinylpyrroles. Heteroatom Chem 8 (6) 495 99. 

In the presence of a double bond at a suitable position, the CO insertion is followed by alkene insertion. In the intramolecular reaction of 552, different products, 553 and 554, are obtained by the use of diflerent catalytic spe-cies[408,409]. Pd(dba)2 in the absence of Ph,P affords 554. PdCl2(Ph3P)3 affords the spiro p-keto ester 553. The carbonylation of o-methallylbenzyl chloride (555) produced the benzoannulated enol lactone 556 by CO, alkene. and CO insertions. In addition, the cyclobutanone derivative 558 was obtained as a byproduct via the cycloaddition of the ketene intermediate 557[4I0]. Another type of intramolecular enone formation is used for the formation of the heterocyclic compounds 559[4l I]. The carbonylation of the I-iodo-1,4-diene 560 produces the cyclopentenone 561 by CO. alkene. and CO insertions[409,4l2]. 

Piperazinothiazoies (2) were obtained by such a replacement reaction, Cu powder being used as catalyst (25. 26). 2-Piperidinothiazoles are obtained in a similar way (Scheme 2) (27). This catalytic reaction has been postulated in the case of benzene derivatives as a nucleophilic substitution on the copper-complexed halide in which the halogen possesses a positive character by coordination (29). For heterocyclic compounds the coordination probably occurs on the ring nitrogen. 

The quatemization reaction of the thiazole nitrogen has been used to evaluate the steric effect of substituents in heterocyclic compounds since thiazole and its alkyl derivatives are good models for such study. In fact, substituents in the 2- and 4-positions of the ring only interact through their steric effects (inductive and resonance effects were constant in the studied series). The thiazole ring is planar, and the geometries of the ground and transition states are identical. Finally, the 2- and 4-positions have been shown to be different (259. 260). 

Cyclic compounds that contain at least one atom other than carbon within their ring are called heterocyclic compounds, and those that possess aromatic stability are called het erocyclic aromatic compounds Some representative heterocyclic aromatic compounds are pyridine pyrrole furan and thiophene The structures and the lUPAC numbering system used m naming their derivatives are shown In their stability and chemical behav lor all these compounds resemble benzene more than they resemble alkenes... 

Radicals derived from heterocyclic compounds by removal of hydrogen from a ring are named by adding -yl to the names of the parent compounds (with elision of the final e, if present). These exceptions are retained ... 

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