is a known amine protecting group may be prepared by reductive coupling of an amine of Formula IV wherein G, J and K are as described above with a ketone of Formula V, wherein P, n and m are as described above, using a borohydride-type reducing agent such as sodium borohydride, sodium cyanoborohydride or sodium triacetoxyborohydride in a reaction-inert solvent such as tetrahydrofuran, methanol or