here is an article about a chirally selective reductive amination for S-fenfluramine
Post 339141
(Rhodium: "Revolutionary novel subst. amphetamine synthesis!", Novel Discourse):
its some rather heavy reading, im not 100% it will be applicable to your desired product, plus im doubtful that its clandestine friendly (i.e. may require alot of hard to get chems) but if possible a chirally selective reaction would assumably be what you want, as d-amp is most likely what your after.
what would really be wonderful is a biosynthetic (and hence most likely chiral) method of reductive amination, there must be some friendly bacteria or plant enzyme out there that would do our dirty work for us, this is the only article that came up when I ran "biosynthetic reductive amination" through TFSE.
Post 187244
(Teonanacatl: "Re: Biosynthetic Pathway", Serious Chemistry)