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Synthesis and mechanism of formation of novel 2,5‐dihydro‐2,5‐diimino‐3,4‐di[( N,N ‐dimethylamino)methylideneamino]pyrroles and 5‐amino‐3,4‐di[( N,N ‐dimethylamino)methylideneamino]‐2 H ‐2‐iminopyrroles
Author(s) -
Alves M. José,
Carvalho M. Alice,
Fernanda M.,
Proença J. R. P.,
Booth Brian L.,
Pritchard Robin G.
Publication year - 1999
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570360129
Subject(s) - chemistry , amine gas treating , ring (chemistry) , medicinal chemistry , dimethylformamide , derivative (finance) , crystal structure , aryl , stereochemistry , organic chemistry , alkyl , financial economics , economics , solvent
Formation of 5‐amino‐3,4‐di[( N,N ‐dimethylarnino)methylidenearnino]‐2 H ‐2‐iminopyrroles 3 from the reaction of (Z)‐ N 1 ‐(2‐amino‐1,2‐dicyanovinyl)‐ N 2 ‐substituted‐formamidines 1 with dimethylformamide diethyl acetal has been shown to occur by initial formation of (Z)‐ N 1 ‐{l,2‐dicyano‐2‐[ N,N ‐dimethylamino)methylideneamino]vinyl}formamidines 8 (isolated), followed by base catalysed cyclisation and imi dazole ring opening by dimethyl amine. The kinetic product of the ring opening reaction is the 2,5‐diimino2,5‐dihydropyrrole derivatives 11, which have been isolated and characterized spectroscopically and by a single crystal X‐ray analysis on the R = Ph derivative. In solution at room temperature the N ‐aryl derivatives undergo a rapid Dimroth rearrangement to give the thermodynamic ally more stable isomer 3 , but compound 11 (R = Me) is much more stable in solution.