2-Carboxymethyl-piperidine-1-carboxylic acid tert butyl ester (2.0 g) was added to [O-(7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate] (3.13 g) in dimethylformamide (10 ml) containing diisopropylethylamine (3.2 g) and the mixture stirred for 15 min. 2-Furoic acid hydrazide (1.04 g) was then added and stirring continued for 16 h. The reaction mixture was diluted with water and extracted with diethyl ether. The combined ether extracts were washed with water, dried and solvent removed at reduced pressure the residue was column chromatographed (silica gel, 20-50% ethyl acetate/hexane) to give the title compound (2.05 g).
