6-Amino-2,6-dideoxy-D-ribo-hexono-1,6-lactam (1a), 6-amino-2,6-dideoxy-D-arabino-hexono-1,6-lactam (2a), 6-amino-2,3,6-trideoxy-L-threo-hexono-1,6-lactam (3a) and per-O-acetyl derivatives 1b-3b were synthesized and their seven-membered lactam ring conformation was studied. 1H and 13C NMR spectra of the named lactams, measured at low temperature, always disclosed the presence of both 1,NC4 and 4C1,N conformations in ratios which were affected mainly by the stereochemistry of cyclohexane. There were no CD extremes over 200 nm found in water solutions of the lactams 1a and 2a, probably owing to the symmetry of the C2-C6 parts of their seven-membered rings. These results contrast with those previously found for the lactams having OH or OAc at C2, and support a concept of the directive role of the C2 substituent in conformation equilibrium.
合成了6-氨基-2,6-二脱氧-D-<斜体>核斜体>-己糖-1,6-内酯(<粗体>1a粗体>)、6-氨基-2,6-二脱氧-D-<斜体>阿拉伯斜体>-己糖-1,6-内酯(<粗体>2a粗体>)、6-氨基-2,3,6-三脱氧-L-<斜体>反斜体>-己糖-1,6-内酯(<粗体>3a粗体>)和per-<斜体>O斜体>-乙酰衍生物<粗体>1b-3b粗体>,并研究了它们七元内酯环的构象。在低温下测量的命名内酯的1H和13C NMR光谱始终显示出1,N<斜体>C斜体>4和4<斜体>C斜体>1,N构象的存在比例,这些比例主要受到环己烷立体化学的影响。在内酯<粗体>1a粗体>和<粗体>2a粗体>的水溶液中没有发现超过200nm的CD极值,这可能是由于它们的七元环的C2-C6部分的对称性。这些结果与先前在C2处具有OH或OAc的内酯的结果相反,并支持C2取代基在构象平衡中的指导作用的概念。