overview[1][2]
3-phenylbut-2-enoic acid can be prepared in one step from triethyl phosphonoacetate and phenylacetaldehyde, and can be used to synthesize 2-position disubstituted indolin-3-one compounds. substituted indolin-3-one structures are widely found in biologically active natural product molecules.
preparation[1]
in a 100 ml two-neck round-bottom flask equipped with a magnetic stir bar, thermometer and condenser, add triethyl phosphonoacetate (1.344 g, 6 mmol), then add thf (20 ml). cool the flask to 5 °c and add nah (60% in mineral oil, 265 mg, 6.6 mmol) portionwise over 10 min. the flask was warmed to approximately 25°c and phenylacetaldehyde (6 mmol) was added to the clear solution via the addition funnel. heat the flask to reflux for 8 hours, then carefully quench the reaction by slowly adding h2o (warning: vigorous gas evolution). the contents of the flask were then poured into water and extracted with ether and washed with 0.1n hcl and brine. the solvent was removed and a crude oil was obtained. the resulting oil, thf (2 ml) and 2 m naoh (2.4 ml, 4.8 mmol) were charged into a 50 ml single-neck round-bottom flask, and heated to reflux for 3 h. dilute the contents with et2o and acidify with concentrated hydrochloric acid. extract twice with et2o, wash with brine, dry over mgso4, filter and concentrate to obtain the product, 1 g of α,β-unsaturated carboxylic acid.
apply[2]
cn201910513544.0 reports the synthesis of 2-position disubstituted indolin-3-one compounds using 3-phenylbut-2-enoic acid.
place (e)-3-phenylbut-2-enoic acid 35.1mg (0.24mmol), 2-phenyl-3h-indol-3-one 41.4mg (0.2mmol), and carbene catalyst 7.00mg ( 0.02mmol), 1h-benzotriazole-1-yloxytripyrrolidinyl hexafluorophosphate 156mg (0.72mmol), cesium carbonate 195.4mmol (0.6mmol) and 4ml of diethyl ether were placed in a 25ml two-neck bottle at room temperature. the reaction solution was reacted for 4 hours. the reaction solution was cooled and concentrated. it was eluted by column chromatography using a mixed solvent with a petroleum ether: acetone ratio of 20:1 as the eluent. the eluate portion of all the products detected was collected and the solvent was evaporated. finally, 64 mg of product was obtained, with a yield of 90%.
main reference materials
[1] from synthesis, 46(5), 607-612, 6 pp.; 2014
[2] [chinese invention] cn201910513544.0 a 2-position disubstituted indoline-3-one compound and its asymmetric synthesis method
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