One-pot synthesis of 2-trifluoromethylchromones

Chromone: A Valid Scaffold in Medicinal Chemistry

“…Another variation of the method involves the acylation step: instead of using the conventional acyl chlorides some authors report the direct application of the carboxylic acids [224] or reaction with acid anhydrides as starting materials [225] . In addition, the use of other bases rather than potassium carbonate, such as metallic sodium [226] , sodium alkoxide [204,[227][228][229] , sodium hydride [204] and potassium or sodium hydroxide [230] , has also been reported.…”

“…The Kostanecki-Robinson reaction has been applied over the years in the synthesis of a large number of chromones [225,249,250] . Despite its wide application, this methodology possesses some drawbacks; one of them is related with the possibility of occurrence of the Baker-Venkatamaran rearrangement and consequent formation of unwanted compounds, namely 3-substituted chromones.…”

A detailed experimental and theoretical study of two novel substituted trifluoromethylchromones. The influence of the bulky bromine atom on the crystal packing

“…Following our reported procedure [23], 2-hydroxypropiophenone (8.7 g, 57.9 mmol), trifluoroacetic anhydride (12.8 g, 60.8 mmol) and pyridine (4,8 ml), were heated with stirring at 120°C for 6 h. The reaction mixture was treated with 1 M hydrochloric acid (3 times, 10 ml) and water (2 times, 10 ml), then the unreacted 2-hydroxypropiophenone was removed by washing several times with 10 mL of 1 M NaOH (controlling its disappearance by TLC). The organic phase was dried with Na 2 SO 4 and the solvent removed in a rotary evaporator to give a white solid.…”

“…The preparation of new 2-trifluoromethylchromones using the above method with trifluoroacetic ethyl ester has been reported by Sosnovskikh's group [19][20][21][22]. More recently, a new chemical pathway involving esterification and cyclization in one step using trifluoroacetic anhydride was developed in our laboratory [23]. This methodology was adopted for the synthesis of 3-methyl-2-trifluorometilchromone (1).…”

Synthesis and Transformation of Halochromones

“…The modified Baker-Venkataraman reaction of alkyl 2-mercaptophenyl ketones 99 with trifluoroacetic anhydride in the presence of triethylamine in refluxing THF gave 2-(trifluoromethyl)-4H-thiochromen-4-ones 100 (Scheme 33) [128]. Castañeda used a similar procedure under solvent-free conditions to prepare 2-trifluoromethylchromones [129]. The pioneering recent synthesis of 3-hydroxy-2-(polyfluoroalkyl)chromones involved the nitrozation of the corresponding 2-(polyfluoroalkyl)chromanones [130].…”