Substituted 4-hydroxy-1,3-dioxanes II react rapidly with PO(NCS)3 to give 4-isothiocyanato-1,3-dioxanes III. The 1H NMR spectra showed that in the isothiocyanate IIIa the predominant stereoisomer has its NCS group in axial position. The addition of benzylamine to the isothiocyanates IIIa and IIIb gave uniform thioureas IVa and IVb with equatorial alkyl groups at 2 and 6 positions and axial thioureido group at 4 position. On the other hand, the isothiocyanate IIIc reacts with benzylamine to give a mixture of three stereoisomeric thioureas V,VI, and VIII. The structure of VI was proved by means of X-ray diffraction analysis; in crystalline form the molecules of VI are present as H-bonded dimers (N-H...O).
替代的4-羟基-1,3-二氧杂环烷II与PO(NCS)3反应迅速,生成4-异硫氰酸酯基-1,3-二氧杂环烷III。1H核磁共振光谱显示,在异硫氰酸酯IIIa中,主要立体异构体的NCS基团处于轴位。将苄胺加入异硫氰酸酯IIIa和IIIb,得到具有2和6位赤道烷基基团以及4位轴向硫脲基团的均一硫脲IVa和IVb。另一方面,异硫氰酸酯IIIc与苄胺反应,生成三种立体异构体硫脲V、VI和VIII的混合物。通过X射线衍射分析证实了VI的结构;在晶体形态中,VI分子以氢键形成二聚体(N-H...O)。