Hydrogen, configuration

The corydaline alkaloids which have been isolated to date in optically active form have all shown positive rotations and positive Cotton effects. Consequently, the absolute stereochemistry at the C-14 position of these alkaloids has been designated by a 14 j8-hydrogen configuration. The structures given above for corydaline (VI), corybulbine (LXI), isocory-bulbine (LXII), thalictricavine (LXIII), and base II (LI) represent the absolute configuration of the naturally occurring (-f )-series. 

Ochromianine, a constituent of the bark of Ochrosia miana, exhibits a mass spectrum virtually identical with that of the isomeric 10-methoxydihydrocorynan-theol. ° The spectroscopic properties of ochromianine suggest that it is a 6-methoxyindole derivative, and that it contains a 3a, 15a-hydrogen configuration, but the configuration at C-20 cannot be regarded as established. The related oxindole A, ochromianoxine (75), accompanies ochromianine in the plant. 

Whereas the strongly negative o.r.d. Cotton effect had predicted that 3 j3-bromoacetoxy-16a-ethyl-16 -<9ano-16, 21-cycIo-Sa-piegna-17,21-diene (113) should possess a 16 -hydrogen configuration, the compound has... 

Electron-configuration notation eliminates the lines and arrows of orbital notation. Instead, the number of electrons in a sublevel is shown by adding a superscript to the sublevel designation. The hydrogen configuration is represented by Is. The superscript indicates that one electron is present in hydrogen s Is orbital. The helium configuration is represented by Is. Here the superscript indicates that there are two electrons in helium s Is orbital. 

In the following, we shall describe the preparation conditions for the three principal phases, a, P and y, distinct by their solubility limits and the critical temperatures for phase transitions or for hydrogen-configuration changes. 

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