TY - JOUR
T1 - The reaction of 2-amino-N′-arylbenzamidines with tetracyanoethene reinvestigated
T2 - routes to imidazoles, quinazolines and quinolino[2′,3′:4,5]imidazo[1,2-c]quinazoline-8-carbonitrile
AU - Mirallai, Styliana I.
AU - Manoli, Maria
AU - Koutentis, Panayiotis A.
PY - 2015/11/18
Y1 - 2015/11/18
N2 - 2-Amino-N′-phenylbenzamidine (1a) reacts with tetracyanoethene (TCNE) to give 2-[2-(2-aminophenyl)-5-imino-1-phenyl-1H-imidazol-4(5H)-ylidene]malononitrile (11a), 4-(phenylamino)quinazoline-2-carbonitrile (5a) and 4-imino-3-phenyl-3,4-dihydroquinazoline-2-carbonitrile (9a). By optimizing the reaction conditions each of the compounds can be isolated as the main product and seven examples of these reactions are described. The [1H-imidazol-4(5H)-ylidene]malononitrile 11a was also independently synthesized in three steps from 2-amino-N′-(2-nitrophenyl)benzamidine (25) and TCNE in an overall yield of 56%. Dimroth rearrangement of either 2-aminophenyl- or 2-nitrophenyl-substituted [1H-imidazol-4(5H)-ylidene]malononitriles 11a or 27 with DBU in hot DCM gave the 2-[2-(2-aminophenyl)- and 2-[2-(2-nitrophenyl)-5-(phenylimino)-3H-imidazol-4(5H)-ylidene]malononitriles 28 (71%) and 34 (59%), respectively. Treatment of the [3H-imidazol-4(5H)-ylidene]malononitrile 28 with ethyl orthoformate in DMA at 165°C gave (Z)-2-[3-(phenylimino)imidazo[1,2-c]quinazolin-2(3H)-ylidene]malononitrile (36) (70%), thermolysis of which gave quinolino[3′,2′:4,5]imidazo[1,2-c]quinazoline-13-carbonitrile (30) (97%).
AB - 2-Amino-N′-phenylbenzamidine (1a) reacts with tetracyanoethene (TCNE) to give 2-[2-(2-aminophenyl)-5-imino-1-phenyl-1H-imidazol-4(5H)-ylidene]malononitrile (11a), 4-(phenylamino)quinazoline-2-carbonitrile (5a) and 4-imino-3-phenyl-3,4-dihydroquinazoline-2-carbonitrile (9a). By optimizing the reaction conditions each of the compounds can be isolated as the main product and seven examples of these reactions are described. The [1H-imidazol-4(5H)-ylidene]malononitrile 11a was also independently synthesized in three steps from 2-amino-N′-(2-nitrophenyl)benzamidine (25) and TCNE in an overall yield of 56%. Dimroth rearrangement of either 2-aminophenyl- or 2-nitrophenyl-substituted [1H-imidazol-4(5H)-ylidene]malononitriles 11a or 27 with DBU in hot DCM gave the 2-[2-(2-aminophenyl)- and 2-[2-(2-nitrophenyl)-5-(phenylimino)-3H-imidazol-4(5H)-ylidene]malononitriles 28 (71%) and 34 (59%), respectively. Treatment of the [3H-imidazol-4(5H)-ylidene]malononitrile 28 with ethyl orthoformate in DMA at 165°C gave (Z)-2-[3-(phenylimino)imidazo[1,2-c]quinazolin-2(3H)-ylidene]malononitrile (36) (70%), thermolysis of which gave quinolino[3′,2′:4,5]imidazo[1,2-c]quinazoline-13-carbonitrile (30) (97%).
KW - Amidines
KW - Cyclization reactions
KW - Heterocycles
KW - Imidazoles
KW - Quinazolines
KW - Tetracyanoethylene
UR - http://www.scopus.com/inward/record.url?scp=84943770070&partnerID=8YFLogxK
U2 - 10.1016/j.tet.2015.09.049
DO - 10.1016/j.tet.2015.09.049
M3 - Article
AN - SCOPUS:84943770070
SN - 0040-4020
VL - 71
SP - 8766
EP - 8780
JO - Tetrahedron
JF - Tetrahedron
IS - 46
M1 - 27146
ER -