and then poured into water 500 ml the precipitate was filtered and dried the title compound was collected as a yellow solid 2 20 g 92 a solution of the 2 methoxy 4 5 methylenedioxy benzaldehyde 16 0 g 0 089 mol diethyl malonate 15 0 ml 0 090 mol piperidine 4 4 ml 0 044 mol and acetic acid 2 5 ml 0 045 mol in benzene 75 ml was stirred at reflux equipped with a dean stark apparatus for 24 h upon removal of the solvent the crude residue was extracted with ethyl acetate and washed with 10 sodium carbonate solution water dried na 2 so 4 after removing the solvent flash chromatography of the residue silica gel 25 ethyl acetate hexane provided the title compound as a yellow solid 26 0 g 91 to a solution of the diethyl 2 2 methoxy 4 5 methylenedioxybenylidene malonate 23 4 g 0 073 mol in ethanol 100 ml was added sodium borohydride 2 8 g 0 073 mol and the mixture was stirred at rt for 5 h the reaction was quenched with water and extracted with ethyl acetate 3 u00d7 200 ml the combined organic extracts were dried na 2 so 4 and evaporated to afford the title.