Potassium phenyltrifluoroborate

To a suspension of potassium phenyltrifluoroborate (92.3 mg, 0.5 mmol), 1-bromon-apthalene (103.5 mg, 0.5 mmol), and K2CO3 (204.5 mg, 1. 5 mmol) in MeOH (0.75 mL) was added Pd(OAc)2 in methanol (1.25 mL, 2 x 10" M) and then the reaction mixture was stirred and heated at reflux for 2 h. The mixture was cooled to room temperature and diluted with water (10 mL). The aqueous phase was extracted with CH2CI2 (3x4 mL). The combined organic extracts were washed with brine (10 mL) and dried (MgSOj). The crude product was then purified via chromatography (silica gel) eluting with hexane to deliver 76.1 mg (75%) of 1-phenylnaphthalene. 

Reactions were run in a sealed tube, using 1 mmol aryl halide, 1.0 mmol potassium phenyltrifluoroborate, 2.5 ppm Pd, 3.7 mmol of Na2CO3, in ethanol/ water (2mL, 1 1 v/v). Applying a 300 W microwave irradiation, the temperature was ramped to 150 °C and held at this value for 5 min, at which point the conversions were complete. 

There has been a review of asymmetric Friedel—Crafts reactions. It has been shown that the rhodium-catalysed reaction of potassium phenyltrifluoroborate with A-tosyl ketimines may lead to products such as (18) with high enantioselectivity. (g) The reaction of A-t-butanesuUinylimino esters with arenes to give products (19) is catalysed by Lewis acids, such as indium triflate, and may lead to enantio-metrically enriched a-glycines. The intramolecular alkylation of hydrogenated 0 tetralins, shown in Scheme 2, using iron(III) or aluminium(III) catalysts yields cis-hexahydrobenzophenanthridines. Formation of a stabilized carbocation intermediate is... 

After the initial report of Miyaura [44], several other modifications were reported (Scheme 4.33). Batey et al. employed potassium aryl- and alkenyltrifluoroborates in place of boronic acids [14aj. The relative rate of reaction was faster with organotriflu-oroborates than with organoboronic acids. Phenyltrifluoroborate (16m) was successfully utilized with 4-nitrobenzaldehyde (70g), giving an 85% yield of 71gm. A <1% yield of 71gm was obtained when the corresponding boronic acid was used. 

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