Facile synthesis of (2R,3R)-phenylalanine-2,3-d2 and NMR study on deuterated gramicidin S1)

Article abstract of DOI:10.1246/bcsj.57.2193

(2R,3R)-Phenylalanine-2,3-d₂ (D-Phe(*)) was synthesized through catalytic reduction of cyclo-(Z)-2,3-dehydrophenylalanyl-D-alanyl-) under an atmosphere of ²H₂ and successive acid hydrolysis in the yield of 80% in high chiral induction. The D-Phe* thus obtained was used for synthesis of [D-Phe *4,4'] gramidicin S (GS*) gramidicin S (GS*). The ¹H NMR spectrum of GS* in DMSO-d₆ showed a sharp singlet at 2.98 ppm for the (3S)-proton of D-Phe* residue. It has been proposed that among rotamers of D-Phe aromatic side chain in GS the one with κ₁ = 180° is predominant. The present observation provides sound evidence for assignments of D-Phe β-protons based on the proposal. (2R,3R)-phenylalanine-2,3-d//2 (d-Phe*) was synthesized through catalytic reduction of cyclo(-(Z)-2,3-dehydrophenylalanyl-D-alanyl-) under an atmosphere of **2H//2 and successive acid hydrolysis in the yield of 80% in high chiral induction. The D-Phe* thus obtained was used for synthesis of left bracket D-Phe***4**,**4** prime right bracket gramicidin S (GS*). The **1H NMR spectrum of GS* in DMSO-d//6 showed a sharp singlet at 2. 98 ppm for the (3S)-proton of D-Phe* residue. It has been proposed that among rotamers of D-Phe aromatic side chain in GS the one with // kappa //1 equals 180 degree is predominant. The present observation provides sound evidence for assignments of D-Phe beta -protons based on the proposal.