Synthesis of a new class of carbinol linked bis-heterocycles via the reaction of 2-(trifluoroacetyl)chromones with indoles and pyrroles

Synthesis of Chromone-Related Pyrazole Compounds

“…This selective and fast procedure, involving an excess of hydrazine hydrate in refluxing ethanol, was applied to a wide variety of 2-substituted chromones 97 to afford several 3(5)-(2-hydroxyaryl)-5(3)-substituted pyrazoles 98 . The substitution at carbon C-2 of the chromone unit can include polyfluoroalkyl [ 62 , 63 ], 1-isopropyl-1 H -indazol-3-yl [ 64 ], 4-(allyloxy)-3-methoxyphenyl-1-yl [ 65 ], 4-chloro-3,4-difluorophenyl-1-yl [ 66 ], 1-aryl-3-(benzofuran-2-yl/naphthalen-3-yl/phenyl/pyridin-3/4-yl, thiophen-2-yl/3-bromothiophen-2-yl)pyrazol-4-yl [ 18 , 19 , 20 , 21 , 67 , 68 , 69 , 70 ], 1-methyl-3-propyl-4-substituted pyrazol-5-yl [ 8 ], 2-(3-methylthiophen-2-yl)-1,3-thiazol-5-yl [ 71 ] substituents (step (i), Scheme 31 ). Using a 5-methyl-3-phenylisoxazol-4-yl group as C-2 substituent, the reaction occurs in the presence of glacial acetic acid to afford 3(5)-(2-hydroxyaryl)-5(3)-(5-methyl-3-phenylisoxazol-4-yl)-1 H -pyrazoles, in good yields (59–83%) (step (ii), Scheme 31 ) [ 72 ].…”

“… Synthesis of 3(5)-(2-hydroxyaryl)-5(3)-substituted pyrazoles 98 from the reaction of 2-substituted chromones 97 with an excess of hydrazine hydrate, using different reaction conditions [ 8 , 18 , 19 , 20 , 21 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 ]. To simplify the schemes, in all the reactions that can include both 3- and 5-(2-hydroxyaryl)pyrazoles, only the 3-isomer will be represented.…”

Reaction of indoles with aromatic fluoromethyl ketones: an efficient synthesis of trifluoromethyl(indolyl)phenylmethanols using K2CO3/n-Bu4PBr in water

“…Recently, Liu and co-workers reported this reaction in the presence of cesium carbonate in acetonitrile ( Figure 2B) [25]. Dinuclear zinc [26], cinchonidine catalysts, and solvent-free conditions [27] have been also utilized for this reaction. The base-catalyzed reaction has a benefit because it may avoid the formation of diindolylmethane and biindoles as byproducts [28].…”

Reaction of indoles with aromatic fluoromethyl ketones: An efficient synthesis of trifluoromethyl-indolyl-phenylethanols using K2CO3/nBu4PBr in water

“…3 Recently, Liu and co-workers reported this reaction in the presence of cesium carbonate in acetonitrile ( Figure 1B) [10]. Dinuclear zinc [11], cinchonidine catalysts [3b], and solvent-free conditions [12] have also utilized for this reaction. The base-catalyzed reaction has a benefit because it may avoid the formation of diindolylmethane and biindoles as by-products [13].…”