Salicylaldehyde, reaction with ethyl acetate

Salicylaldehyde (0.122 mg, 1 mmol), potassium fluoride (KF)-alumina (0.620 g, 0.2 mmol of KF), and a -tosyloxyketone (1 mmol) were mixed in a glass tube and then placed in an alumina bath inside the MW oven and irradiated (intermittently with 1.5 min intervals 130°C). On completion ofthe reaction, followed by TLC examination (hexane ethyl acetate, 9 1), the product was extracted into methylene chloride, the solvent was removed, and the residue was crystallized from ethanol to afford high yield of 2-aroylbenzo[b]furans. 

Reaction Procedure (Scheme 3.2) In a 25 ml round-bottomed flask equipped with a reflux condenser under N2 were placed salicylaldehyde (1 mmol) and 1,2-dibromobenzene (2 mmol), K2CO3 (2 mmol), (PPh3)2PdCl2 (35 mg, 0.05 mmol) and 5 ml DMF. The mfacture was heated to 130 °C for 12 hours before it was cooled to room temperature. The reaction mixture was diluted with diethyl ether (25 mL) and washed with water and brine. The aqueous layer was extracted with diethyl ether (3x25 mL). The organic layers were combined and dried with MgS04, filtered, and the solvent was removed under reduced pressure. The residue was purified by flash chromatography on silica gel (petroleum ether-ethyl acetate, 50 1) to afford the desired product. 

In a 500-ml. round-bottomed flask equipped with a reflux condenser are placed 61 g. (0.50 mole) of salicylaldehyde (Note 1), 88 g. (0.55 mole) of ethyl malonate, and 200 ml. of absolute ethanol. To this mixture are added 5 ml. of piperidine (Note 2) and 0.5 ml. of glacial acetic acid, and the solution is heated under reflux for 3 hours. The hot solution is transferred to a 1-1. Erlen-meyer flask, the reaction flask is rinsed with 20 ml. of ethanol, and the ethanol rinse and 330 ml. of hot water (Note 3) are added to the solution. The product crystallizes readily as the solution cools the mixture is stirred from time to time as crystallization proceeds and is finally stored overnight in a refrigerator. The crystalline product is collected by filtration and washed with a solution made from 80 ml. of 95% ethanol and 120 ml. of water. The material is dried in the air. The yield is 85-91 g. (78-83%) of product melting at 91-93°. 

---