Collect. Czech. Chem. Commun. 1992, 57, 1299-1313

Reactions of PO(NCS)3 with 4-Hydroxy-1,3-dioxanes. Crystal Structure of rel-(2S,4R,5S,6S)-2,6-Diethyl-5-methyl-4-(N'-benzylthioureido)-1,3-dioxane

Juraj Bernáta, Ladislav Kniežoa, Gabriela Birošováa, Miloš Buděšínskýb, Jaroslav Podlahac, Jana Podlahovác and Jiří Novotnýd

a Department of Organic Chemistry, P. J. Šafárik University, 041 67 Košice
b Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6
c Department of Chemistry, Charles University, 128 40 Prague 2
d Department of Solid State Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6


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).