Luisa Citerio

N-halogenoamidines. Part 1. Amino-imidazolines and -imidazoles from N-chloro-N′-arylamidines and enamines

The reaction between N-chloro-N′-arylamidines and enamines derived from aldehydes affords 4-amino-4,5-di-hydro-imidazoles and/or -imidazoles. Imidazole-ring formation was not observed with enamines from ketones and from aldehydes bearing two alkyl groups in the β-position. In the former case chlorinated enamines were obtained, and in the latter a rearrangement to N-(2-amino-2,2-dialkyl)ethylidene-amidines was observed. The reaction mechanism is discussed.

N-haloamidines—III: S-Triazine derivatives from N-halobenzamidines and enamines

Abstract The reaction of N-haloamidines with enamines affords 1,4-dihydro-s-triazine derivatives as the main reaction product. The dihydro derivatives are aromatisable through oxidation with chloranil. The mass spectra of the isolated products are discussed in detail.

1,2-diaryl-4-amino-4,5-dihydro-5,5-disubstituted imidazoles: behaviour in acidic medium

Abstract The behaviour of 1,2,5-triaryl-4-amino-5-methyl-4,5-dihydro-imidazoles 2a–e and 1,2,5,5-tetraphenyl-4-morpholino-4,5-dihydro-imidazole 2f in acidic medium was studied. By heating in 50% H 2 SO 4 , 1,2,4-triaryl-5-methyl-imidazoles and 1,2,4,5-tetraphenyl-imidazole were obtained. When 5-aryl-5-methyl-derivatives were reacted with various nucleophiles in acidic medium the corresponding 4-substituted imidazolines were formed. Generally, only one isomer ( viz E ) was obtained. The 5,5-diaryl-derivative afforded the 1,2,4,5-tetraphenyl-imidazole even in the presence of nucleophiles.

2-Imidazolines. Part 2. Pyrolysis of 1-acyl-4,5-diamino-4,5-dihydroimidazoles: a novel pyrimidine synthesis

1-Acyl-2-phenyl-(or methyl-)4,5-diamino-4,5-dihydroimidazoles (1), when heated in refluxing xylene, afford 2,4-disubstituted-5,6-diaminopyrimidines in good yield. The relative position of the substituent at C-2 or C-4 of the pyrimidine ring depends on the basicity of the amino-group and the nature of the substituent at C-2 of the imidazole ring. The mechanism of the ring expansion is discussed.