Efficient Preparation of Chiral Diamines via Red-Al Reduction of N-Boc-Protected Amino Acid-Derived Secondary Amides.

Conditions have been developed for the selective reduction of N-Boc-protected amino acid-derived secondary amides, avoiding the formation of overreduction and cyclic urea byproducts. The method is showcased by the efficient formal synthesis of NK-1 antagonist LY303870.