The addition of phosphinoboronate ester Ph2PBpin (pin=1,2‐O2C2Me4) (1) to a number of different N‐heterocycles has been investigated. Reaction of 1 with pyridine resulted in highly selective formation of the corresponding 1,4‐addition product, with addition of the electron‐deficient Bpin group to the pyridine nitrogen atom and the phosphido group to the para carbon atom. Conversely, reactions of para‐substituted pyridine derivatives occurred predominately to afford 1,2‐addition products while quinoline reacted to afford the 1,2‐adduct which ultimately isomerized to afford the corresponding 1,4‐addition product. Preliminary computational studies have been undertaken to explore possible pathways for these transformations including transfer of the PPh2− anion from [B(PPh2)2pin]− to the 4‐position of a borenium/boronium activated pyridine and concerted pathways for 1,2‐addition via intramolecular nucleophilic attack of PPh2 at C2 of a Ph2PBpin‐coordinated pyridine via a four‐centered transition state and intramolecular transfer of PPh2 to the 2‐position of a boron‐activated pyridine in a phosphido‐bridged dimer involving a six‐centered transition state.