TY - JOUR
T1 - Reactions of tetracyanoethylene with N′-arylbenzamidines
T2 - A route to 2-phenyl-3 H -imidazo[4,5- b ]quinoline-9-carbonitriles
AU - Mirallai, Styliana I.
AU - Manoli, Maria
AU - Koutentis, Panayiotis A.
PY - 2013/9/6
Y1 - 2013/9/6
N2 - Eight 2-phenyl-3H-imidazo[4,5-b]quinoline-9-carbonitriles 15 are prepared in four steps from N′-arylbenzamidines 11 and tetracyanoethylene (TCNE) in ∼70-90% yields. The transformation involves the initial formation of N-aryl-N′-(1,2,2-tricyanovinyl)benzamidines 12 in 87-99% yields, which in MeCN undergo a 5-exodig cyclization to give the 2-[1-aryl-5-imino-2-phenyl-1H- imidazol-4(5H)-ylidene]malononitriles 13 in 84-92% yields, while in MeOH the (Z)-2-[2-phenyl-4-(arylimino)-1H-imidazol-5(4H)-ylidene]malononitriles 14 are formed in 85-94% yields. The imidazoles 14 can also be prepared directly from imidazoles 13 via a Dimroth rearrangement in either neat MeOH or in DCM with DBU. Subsequent thermolysis of imidazoles 14 in diphenyl ether affords 2-phenyl-3H-imidazo[4,5-b]quinoline-9-carbonitriles 15 in near quantitative yields. Mechanistic rationale is provided for all transformations.
AB - Eight 2-phenyl-3H-imidazo[4,5-b]quinoline-9-carbonitriles 15 are prepared in four steps from N′-arylbenzamidines 11 and tetracyanoethylene (TCNE) in ∼70-90% yields. The transformation involves the initial formation of N-aryl-N′-(1,2,2-tricyanovinyl)benzamidines 12 in 87-99% yields, which in MeCN undergo a 5-exodig cyclization to give the 2-[1-aryl-5-imino-2-phenyl-1H- imidazol-4(5H)-ylidene]malononitriles 13 in 84-92% yields, while in MeOH the (Z)-2-[2-phenyl-4-(arylimino)-1H-imidazol-5(4H)-ylidene]malononitriles 14 are formed in 85-94% yields. The imidazoles 14 can also be prepared directly from imidazoles 13 via a Dimroth rearrangement in either neat MeOH or in DCM with DBU. Subsequent thermolysis of imidazoles 14 in diphenyl ether affords 2-phenyl-3H-imidazo[4,5-b]quinoline-9-carbonitriles 15 in near quantitative yields. Mechanistic rationale is provided for all transformations.
UR - http://www.scopus.com/inward/record.url?scp=84883772188&partnerID=8YFLogxK
U2 - 10.1021/jo4013699
DO - 10.1021/jo4013699
M3 - Article
C2 - 23895360
AN - SCOPUS:84883772188
SN - 0022-3263
VL - 78
SP - 8655
EP - 8668
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
IS - 17
ER -