ABSTRACT
Despite a large number of synthesis procedures for pyrazoles known today, those directly employing primary amines as substrates are rare. Herein, we report an original method for the preparation of N-alkyl and N-aryl pyrazoles from primary aliphatic or aromatic amines as a limiting reagent of the reaction. The protocol utilizes no inorganic reagents and requires a short reaction time, mild conditions, and the use of structurally simple and commercially available starting reagents. During this study, pyrazoles containing a wide variety of N-substituents were obtained using the same procedure for both aliphatic and aromatic amines.
Subject(s)
Amines , Pyrazoles , Catalysis , Indicators and ReagentsABSTRACT
32-Hetero-5,6-dimethoxyphenanthrisapphyrins-macrocycles that link structural features of polycylic aromatic hydrocarbons and expanded porphyrins-were obtained in a straightforward [3+1] condensation reaction of dimethoxyphenanthritripyrrane and 2,5-bis(arylhydroxymethyl)heterocyclopentadienes. The highly folded conformation of formally 4 n π-electron macrocycles causes them to manifest only limited macrocyclic π conjugation as explored by means of NMR spectroscopic and X-ray structural analyses, and supported by DFT calculations. Although protonation does not change their π-conjugation characteristics, the cleavage of ether groups at the phenanthrenylene moiety yields nonaromatic 32-hetero-5,6-dioxophenanthrisapphyrins.
