1202003-49-3

White to off-white powder.

(S)-2-((((9H-Fluoren-9-yl)methoxy)carbonyl)amino)-6-((tert-butoxycarbonyl)amino)-2-methylhexanoic acid is a reagent in the preparation/biological evaluation of a vapreotide analogs containing (S)-α-methyl-lysine.

Benzyl (2R,3S)-(?)-6-oxo-2,3-diphenyl-4-morpholinecarboxylate (4) was successively alkylated with methyl iodide and 1,4-diiodobutane using a base. In each alkylation step anti-alkylated product formed exclusively. The iodo group was displaced with azide, which served as a precursor for the side-chain amino function. Catalytic hydrogenation with concomitant cleavage of the chiral auxiliary afforded (L)-α-Me-Lys-OH (9) in a total of four steps in good yield. (L)-Fmoc-α-Me-Lys(Boc)-OH (16) was obtained from 9 via regioselective benzyloxycarbonylation. Alternately, (L)-Fmoc-α-Me-Lys(Boc)-OH (16) was obtained via Staudinger reduction of azide (8) in a total of six steps in good yield.