Formation constants in water of 1:1 benzo-18-crown-6 (B18C6)–metal ion complexes and the B18C6 solubility in water were determined at 25 °C by conductometry or potentiometry with ion-selective electrodes and spectrophotometry, respectively. The selectivity sequences of B18C6 for metal ions in water are Pb2+>Ba2+>Sr2+>Ag+>K+>Tl+>Na+>Rb+. In each case of alkali and alkaline earth metal ions, the more closely a metal ion fits into the B18C6 cavity, the more stable is the B18C6–metal ion complex. Although the solvation power of water for an alkali metal ion is not the largest of all solvents, the formation constant of a given B18C6–alkali metal ion complex in water is by far the smallest of all solvents. The transfer activity coefficients (γ) from water to nonaqueous solvents of the B18C6–metal ion complexes were then calculated from the formation constants of the B18C6 complexes, γ values of B18C6 (obtained from solubilities of B18C6), and γ values of the uncomplexed metal ions. The γ value of B18C6 is larger than those of B18C6–alkali metal ion complexes. This shows that when B18C6 forms a complex with an alkali metal ion, the B18C6 complex becomes more soluble in nonaqueous solvents than in water, compared with uncomplexed B18C6.

The conversion of the 4-oxo-2-benzoyl-l,2,3,4-tetrahydro-|8-carbolines la and lb, respectively, into their corresponding 4-amino-(3-carbolines 2a and 2b was effected in 70% yield in refluxing hydrazine. In contrast, phenylhydrazine, when heated with the 4-oxo derivative lb, gave the pyridodiindole 18a. This compound derives its origin from an initial Fischer indole cyclization, followed by loss of the 2-benzoyl group and aromatization to the /3-carboline. During investigation of the scope and mechanism of this new amination-oxidation reaction, it was found that an acidic hydrogen atom (position 2, NH) to the carbonyl group (C-4) was necessary to drive the reaction to completion. Although phenylhydrazones such as 20b and 20c, which carry electron-withdrawing groups, led to the formation of 2b at the expense of the Fischer indole products 18b and 18c, respectively, the yields in this sequence were only moderate. Hydrazine, consequently, appears to be the reagent of choice to effect this amination-oxidation reaction since Fischer indole cyclization cannot compete in this process.

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The reaction of diethyl oxalate with ethereal oxygen-containing diamines under high-dilution conditions gave 2 : 2 reaction products, 22-, 28-, and 34-membered macrocyclic amides in good yields. From the 2 : 1-mixed reaction between diethyl oxalate and the diamines, acyclic 2 : 1 and 3 : 2 reaction products were isolated at a ratio of ca. 9 : 1. The intermediate 2 : 1 and 3 : 2 reaction products led to the 2 : 2 reaction products mentioned above and the 3 : 3 reaction products, 33-, 42-, and 51-membered macrocyclic amides, respectively, upon reaction with additional corresponding diamines. Also, other macrocyclic amides were synthesized by combining the 2 : 1 reaction products and diamines.

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Aus dem Ammoniumdithiocarboxylat (II), das durch Behandlung von Cyclohexanon (I) mit einem Überschuß an CS2 in wäßrigem Ammoniak entsteht, wird die Titelverbindung (III) mit Essigsäure freigesetzt.