Substituted single-rings

Aromatics-single ring, mono substituted by isoparaffins 2 2.99 0.0264 37.5 62.6... 

Organic synthesis 33 [OS 33] Nitration of substituted single-ring aromatics... 

Figure 16.8 Comparison of feed and product catalysts, (b) the formation of different composition from light cycle oil hydrocracking distributions of substituted single-rings showing (a) essentially complete conversion depending on catalyst composition. Catalysts of feed two-ring compounds on four different 1—4 differ in metal and acid function.

The most important transformations of phosphorinanes involve oxidation (by air, 3% H202, Bu OOH, O3, N204 (especially) or other oxidants). The products, 1-R-l-oxophosphorinanes (9 R = alkyl, aryl, OR, NR2, Cl, etc.) are much more stable than the phosphorinanes (P-CN = 3), and are mostly crystalline. A host of X-ray determinations of single crystals have been described. Oxidation with N204 (but also with some other oxidants) occurs without inversion <71PAC(25)549) and is therefore very useful for structure determinations of ring-substituted phosphorinanes (P-C1V = 3). The reverse reaction, reduction of the P=0 bond, is also an important route to three-coordinate phosphorinanes of known... 

SAR studies have shown that a weakly basic imidazole or 1,2,4-triazole rings substituted only at the N-l position are essential for activity. The substituent must be lipophilic in character and usually contains one or more five or six membered ring systems, some of which may be attached by an ether, secondary amine or thioether group to the carbon chain. The more potent compounds have two or three aromatic substituents, which are singly or multiply chlorinated or fluorinated at positions 2, 4 and 6. These nonpolar structures give the compounds a high degree of lipophilicity, and hence membrane solubility. 

Fusion of a benzene ring onto a five-membered heterocycle produces a change in the positional reactivity order associated with the latter. In the single-ring, five-membered heterocycles, 2-substitution is favored over 3-substitution. This can be explained in valence-bond terminology as due to there being three canonicals for the transition state for the former, and only two for the latter (see Chapter 6, Section 10.A). 

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