6,10-Dibenzyl-N,N-dimethyl-N,N,N,N-tetrakis(4-methylbenzyl)-1,4-dioxaspiro[4.5]decane-(2S,3S)-diylbis(methylammonium) bis(tetrafluoroborate) is a catalyst used in the diastereoselective synthesis of 11C-labeled dipeptides by stereocontrolled [11C]alkylation of glycine Schiff bases.