Structural analogs

Write a resonance form for guanine in which the six membered ring has an electronic structure analogous to benzene Show all unshared pairs... 

Diaziridines, discovered in 1958, six years after the oxaziridines, were almost immediately realized to be structural analogs of oxaziridines. Like these they showed oxidizing properties unexpected for other classes of organic nitrogen compound. Properties in common with oxaziridines include the rearrangement to open chain isomers on heating above 100 °C (for several diaziridines), and their hydrolytic behavior in acidic media, which leads to carbonyl compounds with conservation of the hetero-hetero bond. 

The last-mentioned property of a synthetic process, i.e. versatility, is frequently an important consideration in research on optimally effective therapeutic agents in which the synthesis of a large series of structural analogs from a single intermediate is desirable. This aspect of the problem-solving environment can play a decisive role in synthetic design. 

In the early work, benzene formed the basis of a variety of multi-armed structures. Analogs bearing from 2—6 arms were prepared and compared for cation binding ability. The only indication of mode of synthesis for the hexa-substituted benzene derivative is that it was obtained on reaction of benzene-hexakis(methanethiol) and l-bromo-3,6,9-trioxatridecane . The reaction is illustrated in Eq. (7.6), below, devoid of reaction conditions and yields which were not specified. 

Structural analogy of aliphatic amino ketones can be found in the heterocyclic series. A simple example of such compounds is /) -octahydro-7-quinolone (767) which, as a vinylog of an amide, can possess enonamine-enolimine tautomerism (168). 

The structural analogy with the dicarbaborane C2B3H5 (56) is obvious. Likewise, pyrolysis of a mixture of B2CI4 and PCI3 yields [closo-... 

R2GaAsBu2)2 (R = Me, Bu ) have structures analogous to A more complex 12-... 

From Pu onwards, sesquioxides become increasingly stable with structures analogous to those of Lu203 (p. 1238) Bk02 is out-of-sequence but this is presumably due to the stability of the f configuration in Bk. For each actinide the C-type M2O3 structure (metal CN = 6) is the most common but A and B types (metal CN = 7) are often also obtainable. 

These products were originally named indil derivatives, since they are structurally analogous to the bettor known compound benzil (CeHsCOCOCeHs) and its derivatives. 

Heterocyclic structures analogous to the intermediate complex result from azinium derivatives and amines, hydroxide or alkoxides, or Grignard reagents from quinazoline and orgahometallics, cyanide, bisulfite, etc. from various heterocycles with amide ion, metal hydrides,or lithium alkyls from A-acylazinium compounds and cyanide ion (Reissert compounds) many other examples are known. Factors favorable to nucleophilic addition rather than substitution reactions have been discussed by Albert, who has studied examples of easy covalent hydration of heterocycles. 

There are numerous families of organic compounds, with structures analogous to hydrocarbons, that contain other atoms (e.g., O, N, S, Cl) besides C and H. Classification is done in accordance with the structural theory on the basis of functional groups present. The atom or atomic grouping that characterizes a particular family and also determines the properties of its members is called a Junctional group. Table 2-42 contains a selected list of common functional groups and examples of... 

In choosing an initiator the strength of the R-X bond in both the initiator and the dormant propagating species formed should be considered. It is common practice to use a compound such that the radical generated is a monomeric or low molecular weight species structurally analogous to the propagating radical. Thus,... 

Each polytripeptide chain is twisted around a threefold screw axis and exists in a secondary structure, analogous to the left-handed polyproline II-helix, i.e. with transposition of the peptide bond (pitch 8.4 A, 3 amino acids) (Figs. 2,3). 

Kekule (1866, vol. II, p. 716) realized that the diazo compounds were structurally analogous to their most important derivatives, the azo compounds, and he therefore described their constitution with the formula C6H5-N = N-X. The fact that the diazo compounds are much less stable than the azo species was thought to detract from Kelule s formulation. Blomstrand (1869, 1875) proposed the structure C6H5 — N — X and, in analogy to the ammonium salts, the name azoammonium . 

Combeau, C. Carlier, M.-F. (1988). Probing the mechanism of ATP hydrolysis on F-actin using vaitadate and the structural analogs of phosphate BeF j and AIF J. J. Biol. Chem. 263,17429-17434. 

There is an obvious structural analogy between cw-vinylene sets, 1, and ortho-substituted benzene sets, 2. The possible existence of proximity effects in... 

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