Regiospecific synthesis of 3H‐pyrido[2,3‐b][1,4]diazepin‐4(5H)‐ones viahaloform reaction with the isolation of N³‐[3‐oxo‐4,4,4‐trichloroalk‐1‐en‐1‐yl]‐2,3‐diaminopyridine intermediates

Abstract

The synthesis of a novel series of analogous intermediates N3‐[1‐alkyl(aryl/heteroaryl)‐3‐oxo‐4,4,4‐trichloroalk‐1‐en‐1‐yl]‐2,3‐diaminopyridines and N2‐(methanesulfonyl) [Cl3CC(O)CHCRNH(C5H3N)NHY], where R = H, Me, C6H5, 4‐FC6H4, 4‐ClC6H4, 4‐BrC6H4, 4‐CH3C6H4, 4‐OCH3C6H4, 4,4′‐biphenyl, 1‐naphthyl, 2‐thienyl, 2‐furyl, and Y = H, SO2Me, is reported. A new corresponding series of 2‐aryl/heteroaryl‐3H‐pyrido[2,3‐b][1,4]diazepin‐4(5H)‐ones obtained from intramolecular cyclization reaction of the first series of trichloroacetyl enamines or from the direct cyclocondensation reaction of 4‐methoxy‐1,1,1‐trichloalk‐3‐en‐2‐ones with 2,3‐diaminopyridine, under mild conditions, is also demonstrated. J. Heterocyclic Chem., (2009).

Regiospecific Synthesis and Structural Studies of 3,5-Dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-ones and Comparison with 1,3-Dihydro-2H-benzo[b][1,4]diazepin-2-ones

“…The same group later isolated and characterized the open intermediate formed by addition of the 3-aminopyridine group to the β-olefinic carbon of the vinyl ketone, cyclization of which led to compound 17 ( Scheme 3 ). 21 …”

“…This residue was washed with ethyl ether to give compound 17 (0.20 g, 61%) as a pale yellow solid: mp 270.7 °C (EtOH), lit. mp 264–266 °C, 18 258 °C, 19 250–252 °C; 21 1 H NMR (400.13 MHz, DMSO- d 6 ) δ 10.95 (s, 1H, H1), 8.34 (dd, 3 J H7 = 4.6, 4 J H6 = 1.8 Hz, 1H, H8), 8.08 (dd, 3 J H m = 7.7, 4 J H p = 1.2 Hz, 2H, H o ), 7.85 (dd, 3 J H7 = 7.9, 4 J H8 = 1.8 Hz, 1H, H6), 7.55 (m, 3H, H m , H p ), 7.32 (dd, 3 J H6 = 7.9, 3 J H8 = 4.6 Hz, 1H, H7), 3.60 (s, 2H, H3); 13 C NMR (100.62 MHz, DMSO- d 6 ) δ 166.2 (C2), 159.4 (C4), 146.1 (C8), 142.5 (C9a), 136.9 (C i ), 136.5 (C6), 134.6 (C5a), 131.1 (C p ), 128.8 (C m ), 127.8 (C o ), 120.1 (C7), 40.3 (C3); 15 N NMR (40.54 MHz, DMSO- d 6 ) δ −231.3 (N1), n.o. (N5), −84.8 (N9); anal.…”

General Pathway for a Convenient One-Pot Synthesis of Trifluoromethyl-Containing 2-amino-7-alkyl(aryl/heteroaryl)-1,8-naphthyridines and Fused Cycloalkane Analogues

“…Unfortunately, reactions using β-alkoxyvinyl trifluoromethyl ketones and 2-aminopyridine in an attempt to obtain the respective cyclic structure only resulted in the isolation of trifluoroacetylenamine derivatives [ 32 ]. On the other hand, reactions using β-alkoxyvinyl trifluoro(chloro)methyl ketones and 2,3-diaminopyridine have been successfully employed in the synthesis of 3 H -pyrido[2,3- b ][1,4]diazepinols [ 31 , 32 ] or diazepinones [ 31 , 33 ].…”

“…Although the reactions of 4-alkoxy-4-alkyl(aryl/heteroaryl)-1,1,1-trifluoroalk-3-en-2-ones with primary and secondary amines have been well documented [ 28 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ], there are no reports in the literature dealing with β-alkoxyvinyl trifluoromethyl ketones as electrophilic precursors and 2,6-diaminopyridine (2,6-DAP) as nucleophilic precursor. Considering the importance of trifluoromethylated heterocycles, as an extension of our research the purpose of this paper is to report the results of a chemical behavior study of the reactions of 4-alkoxy-4-alkyl(aryl/heteroaryl)-1,1,1-trifluoroalk-3-en-2-ones and 2-trifluoroacetyl-1-methoxycycloalkenes 1 with 2,6-DAP, a symmetrical heteroaromatic diamine, aiming at the synthesis of new nitrogen-containing trifluoromethylated heterocycles with conventional procedures ( Scheme 1 ).…”