The reaction of aldehydes, amines and TMSCN in the presence of 2-iodoxybenzoic acid (IBX) and tetrabutylammonium bromide (TBAB) afforded alpha -iminonitriles, e.g. 4-MeOC6H4C(C==N):NCH2CH2Ph, in good to excellent yields under mild conditions. The presence of TBAB is essential for this transformation. The methodol. was applied to a two-step synthesis of indolizidine I via a microwave-assisted intramol. cycloaddn. of alpha -iminonitrile PhCH:CHC(C==N):N(CH2)3CH:CH2. [on SciFinder (R)]