2,3,5,6-テトラフェニルピペラジンの立體異性(I)

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概要

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• The stereochemical study of heterocyclic compounds containing nitrogen in the ring is considered to be important to the study of the constitution and function of alkaloids, vitamins and ferments, because those cyclic systems are the important frame of such natural substances. The present author studied the stereoisomerism of several heterocyclic compounds containing nitrogen, such as 2, 3-diphenyl-2, 3-dihydropyrazine and 2, 3-diphenyl-piperazine. Connected with those studies, the stereoisomerism of 2, 3, 5, 6-tetraphenyl-piperazine (the following formula I) was studied by the author and a part of the result obtained is reported in this paper. It was considered to be probable that the spatial configuration of the piperazine ring might be similar to that of the cyclohexane ring and only the chair form might exist. In the chair form configuration of 2, 3, 5, 6-tetraphenyl-piperazine, there are seven possible geometrical isomers, A, B, C, D, E, F and G, represented in Fig. I, in which isomers the relation of the spatial position of four hydrogen atoms and four phenyl groups differs from one other. Of these isomers, B, C and E may be resolvable into optical active antipodes respectively. 2, 3, 5, 6-Tetraphenyl-piperazine was obtained from 2, 3, 5, 6-tetraphenyl-pyrazine (amaron) and trans-2, 3, 5, 6-tetraphenyl-2, 3-dihydropyrazine. Amaron, obtained by the reaction of meso-stilbenediamine and benzil, was reduced by sodium and boiling amylalcohol, and four isomers, α (colorless plate crystals, mp 161-2°), β (colorless fine prism crystals, mp 209.5-210.5°), γ (colorless prism crystals, mp 266-8°) and ε (colorless plate crystals, mp 300-2°) were separated by the fractional crystallisation from acetone. As seven possible geometrical isomers are supposed to be produced from amaron, the configuration of these four isomers cannot be established from the result of the reduction. Trans-2, 3, 5, 6-tetraphenyl-2, 3-dihydropyrazine, mp 246-7°, obtained by the condensation of (d+1)-stilbenediamine and benzil, was reduced by sodium and boiling amylalcohol. Besides four isomers above mentioned, amaron, which is produced by the removal of two trans-hydrogen atoms of 2-and 3-carbon atoms of tetraphenyl-2, 3-dihydropyrazine, was obtained. If there is no removal of hydrogen atoms, the phenyl groups of 2- and 3-carbon atoms of these four tetraphenyl-piperazine isomers is considered to have a trans-configuration. However, as the dehydrogenated compound, amaron, was obtained, it is considered that in the first place amaron may be produced and, next, it may be reduced, and therefore the configuration of isomers obtained from amaron can not be determined. In order to avoid the removal of hydrogen atoms which may occur at higher temperature, reduction at low temperature by aluminium amalgam in the ethereal solution containing some water, was done. In this case, a new isomer, δ (colorless fine needle crystals, mp 291-2゜) was obtained with γ-isomer, and amaron was also obtained. From the results above mentioned can only be concluded that the five isomers obtained are probably five among-seven geometrical isomers which are expected to exist from the assumption that the configuration of the piperazine ring is chair form. The study of the configuration of isomers obtained and also that of the stereoisomerism of other tetra-substituted piperazines are now being continued and those results will be reported in the next papers.

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著者

• 林 太郎

  Department Of Chemistry Faculty Of Science Ochanomizu University

• 林 太郎

  Laboratory of Chemistry, Faculty of Science, Ochanomizu University

関連論文

• The Stereoisomerism of 2, 4, 5-Tricyclohexyl-imidazole
• On Symmetrically Di-substituted Urea
• 2,3,5,6-テトラフェニルピペラジンの立體異性(I)

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