(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′] gramicidin 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)-苯丙
氨酸-2,3-d2 (d-Phe*)通过环(-(Z)-2,3-脱氢苯丙
氨酰-d-丙
氨酰-)在2H2气氛下催化还原和连续反应合成在高手性诱导下酸
水解产率达80%。由此获得的d-Phe*用于合成[d-Phe*4,4']
短杆菌肽S(GS*)。
DMSO-d6 中 GS* 的 1H NMR 谱显示 d-Phe* 残基的 (3S)-质子在 2.98 ppm 处有尖锐的单线态。有人提出,GS d-Phe 芳香族侧链的旋转异构体中,κ1=180° 的旋转异构体占主导地位。目前的观察结果为基于该提议的 d-Phe β-质子分配提供了可靠的证据。