SYNTHESIS OF CHIRAL 1,2,4-TRIAMINOBUTANES

(S)-5-(Azidomethyl)-2-pyrrolidone, obtained by the Mitsunobu reaction, was reduced to (S)-5-(aminomethyl)-2-pyrrolidone which was hydrolysed to (S)-4,5-diaminovaleric acid. The acid, after acylation with i-butyl or with (1R, 3R, 4S)-menthyl chloroformate, underwent a Curtius reaction yielding the corresponding (S)-1,2-dialkoxycarbonyl-1,2,4-triaminobutane. Alternatively, (S)-5-(aminomethyl)-2-pyrrolidone was subjected to exhaustive t-butoxycarbonylation followed by ring-cleavage with ammonia to give (S)-N4,N5,N5-triboc-4,5-diaminovaleramide and was converted by a Hofmann rearrangement to (S)-N1,N2-di-t-butoxy carbonyl-4-methoxycarbonyl-1,2,4-triaminobutane.