piperidine in pyridine malonic acid was added to soln. p-formylbenzeneboronic acid in pyridine at 25°C, piperidine was added and refluxed under N2 for 13 h; solvent was removed in vacuo, residue was taken up in water and acidified with concd. HCl, ppt. was collected, washed with water and dried in vacuo; elem. anal.;