Piperidino

CHj-CIUCgH,), (CH2) -N ) 3- (2,2-Diphenyl-ethyl j-5- ( 2-piperidino-ethyl)-... Prenoxdiazin 49... 

The N-basicity of the commonly used amines (pyrrolidine > piperidine > morpholine) drops by 2-3 orders of magnitude as a consequence of electron pair delocalization in the corresponding enamines. This effect is most pronounced in morpholino enamines (see table below). Furthermore there is a tendency of the five-membered ring to form an energetically favorable exocyclic double bond. This causes a much higher reactivity of pyrroUdino enamines as compared to the piperidino analogues towards electrophiles (G.A. Cook, 1969). 

Attempts to prepare the diprOpylamino-5-sulfonic acid by sulfonation in oleum failed (385). With 2-piperidino-4-methylthiazole Ochiai reports cleavage of the 2-piperidino ring (391). 

Also, piperidino- and morpholino- are preferred to 1-piperidyl- and 4-morpholinyl-, respectively. 

Denotes position of double bond, t For 1-piperidyl, use piperidino. 

Other Radioprotective Chemicals. The bis-methylthio- and methylthioamino-derivatives of 1-methylquinolinium iodide and l-methylpyridinium-2-dithioacetic acid provide reasonable protection to mice at much lower doses than the aminothiols, which suggests a different mechanism of action (139). One of these compounds, the 2-(methylthio)-2-piperidino derivative of the l-methyl-2-vinyl quinolinium iodide (VQ), interacts with supercoUed plasmic DNA primarily by intercalation. Minor substitutions on the aromatic quinolinium ring system markedly influence this interaction. Like WR-1065, VQ is positively charged at physiological pH, and the DNA-binding affinities of VQ and WR-1065 appear to be similar. 

Halo-substituted 3-hydroxypyridazin-6(lFf)-ones react in some instances by cine substitution. For example, 4-chloro-l-methyl-2-phenylpyridazin-6(lFf)-one, when treated with piperidine, yields a mixture of the corresponding 4- and 5-piperidino isomers in nearly equal amounts. 

The reactivity of halogens in pyridazine N- oxides towards nucleophilic substitution is in the order 5 > 3 > 6 > 4. This is supported by kinetic studies of the reaction between the corresponding chloropyridazine 1-oxides and piperidine. In general, the chlorine atoms in pyridazine A-oxides undergo replacement with alkoxy, aryloxy, piperidino, hydrazino, azido, hydroxylamino, mercapto, alkylmercapto, methylsulfonyl and other groups. 

Dithiolylium-4-olate, 5-phenyl-2-piperidino-IR, 6, 818 <76CB740, 78CB2021)... 

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