Non-aromatic Rings

Membered Non-Aromatic Ring Compounds a) Pyrazoline Compounds... 

Mitoxantrone (mitozantrone) (Figure 3.57) is a synthetic analogue of the anthracyclinones in which the non-aromatic ring and the aminosugar have both been replaced with aminoalkyl side-chains. This agent has reduced toxicity compared with doxorubicin, and is effective in the treatment of solid tumours and leukaemias. 

Ring transformations are common in pharmaceuticals. The API lorazepam containing a seven-membered non-aromatic ring can lose a molecule of water and rearrange with the driving force being formation of a six-membered aromatic pyrimidine ring (Fig. 115) (165). 

Polytrimethylsilylated piperidines have been obtained through the reductive silylation of quinoline (Section III.B.2.d). Among these compounds are SMA derivatives that are readily oxidized in the presence of air and hydrolyzed into pyridine derivatives. Trimethylsilyl groups on the non-aromatic ring were found to be in an all-fraws relationship.179... 

X-ray structural studies of the anions of germoles have recently stimulated a great deal of interest . Crown ethers (12-crown-4 for Li and 16-crown-6 for K) were used in monometallation reactions, giving free germacyclopentanienide ions . They have a non-aromatic ring with a pyramidal germanium center (Figure 5). 

RMC, that allows for the formation of non-aromatic rings which are responsible for the curvature and cross-linking in carbon plates. We combined our atomistic approach with Simulated Aimealing (SA) to develop a reconstruction method [4] that gives better fits to the experimental data than the original RMC technique. 

Altona, C., Geise, H. J., and Romers, C. Conformation of non-aromatic ring compounds-XXV. Geometry and conformation of ring D in some steroids from X-ray structure determinations. Tetrahedron 24, 13-32 (1968). 

The substitution of —CH= by —N= in aromatic rings has been one of the most successful applications of classical isosterism (see Section III.D.). Interchange of trivalent atoms are found also in non aromatic rings. For example the 4-dimethylamino-antipyrine and its carba-isostere are about equally active as antipyretics (Figure 15.7). 

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