The first application of 4-alkoxy-1,1,1-trifluoroalk-3-en-2-ones in a three-component condensation protocol for the synthesis of 3-acyl-4-aryl-2-(trifluoromethyl)-2-hydroxy-3,4,7,8-tetrahydro-2H-chromen-5(6H)-ones
This article reports a convenient and general method for the regioselective synthesis of a new series of 2‐alkyl(aryl)‐8‐methyl‐4‐trifluoromethyl‐7‐aminoquinolines in 86–93% yields, from cycloaromatization reactions of N‐(oxotrifluoroalkenyl)‐2,6‐diaminotoluenes in a strongly acidic medium polyphosphoric acid and absence of solvent. The enaminoketone intermediates were easily isolated from the reaction of 4‐alkoxy‐4‐alkyl(aryl)‐1,1,1‐trifluoroalk‐3‐en‐2‐ones [CF3C(O)CH═C(R)OR1, where R = H, Me, Ph, 4‐FPh, 4‐BrPh, 4‐MePh, and R1 = Me, Et] with 2,6‐diaminotoluene (2,6‐DAT) in methanol under mild conditions, in 46–70% yields. Another synthetic route also allowed the regioselective synthesis of 2‐aryl(heteroaryl)‐4‐methyl‐4‐trifluoromethyl‐7‐aminoquinolines from direct cyclocondensation reactions of 4‐alkoxy‐4‐aryl(heteroaryl)‐1,1,1‐trifluoroalk‐3‐en‐2‐ones with 2,6‐diaminotoluene in methanol under mild conditions, in 21–36% yields.
Two new series of 1,1 0 -carbonyl-bis[3-aryl(heteroaryl)-5-trihalomethyl-1H-pyrazoles], where aryl ¼ C 6 H 5 , 4-CH 3 C 6 H 4 , 4-FC 6 H 4 , 4-OCH 3 C 6 H 4 , 4-NO 2 C 6 H 4 , 4,4 0 -BiPh, 1-naphthyl, and heteroaryl ¼ 2-thienyl and 2-furyl have been synthesized, in a one-pot methodology, from the reaction of 4-methoxy-4-aryl(heteroaryl)-1,1,1-trihalobut-3-en-2-ones with 1,3-diaminoguanidine monohydrochloride. The heterocycles were obtained regioselectively in good yields (62-86%) and in a short reaction time. Ring-opening reactions with 1,2-dinuleophiles and the synthesis of ethyl carboxylate derivative from a pyrazolycarbohydrazide is also reported.
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