Centrally chiral compounds of nitrogen and phosphorus

Unsymmetrically substituted amines (28) are potentially chiral because of the pseudo-tetrahedral arrangement of the three groups and the lone pair. Under normal conditions, however, there is rapid inversion at the nitrogen centre (racemisation) which prevents the separation of enantiomers. Only in special cases where the nitrogen is in a small ring with electron-withdrawing groups present have compounds 

As soon as the lone pair is fixed by bonding to an electrophile, inversion is prevented and therefore both the quaternary ammonium 

As well as illustrating the synthesis of chiral phosphines this sequence introduces two other types of chiral phosphorus compound the phosphinate ester (36) and the phosphine oxide (37). In fact any tetracoordinate phosphorus compound with four different groups attached to the tetrahedral centre is chiral. The chiral compounds of phosphorus have been reviewed, 

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