L,3-Oxazinane-2-thiones

Abstract The high synthetic versatiUty exhibited by the isothiocyanato motif has allowed its use as a building block in the preparation of a plethora of derivatives. When present in carbohydrates, the strong electrophilicity shown by isothiocyanates, together with the possibility of undergoing cycloaddition reactions has made it possible to access a broad spectrum of heterocyclic compounds, of either synthetic or pharmaceutical interest. Among them, noteworthy are 1,3-oxazolidine- and l,3-oxazinane-2-thiones (cyclic thiocarbamates), 2-amino-2-oxazolines (cyclic isoureas), 2-amino-2-thiazolines (cyclic isothioureas), nucleosides, and spironucleosides. 

In this work, we will describe the use of sugar-derived isothiocyanates in the stereocontrolled synthesis of heterocychc derivatives, such as 1,3-oxazohdine- and l,3-oxazinane-2-thiones (5- and 6-membered cyclic thiocar-bamates, respectively), 2-amino-2-oxazolines (5-membered cyclic isoureas), nucleosides, spiroglycosides and spironucleosides, and compounds that are simultaneously pseudo-C- and N-nucleosides. 

The preparation of l,3-oxazolidine-2-thiones and l,3-oxazinane-2-thiones is a challenging task as compoimds exhibiting these structures show interesting... 

FIGURE 1 Heterocyclic structures incorporating CO2 and related motifs. (A) l,3-dioxolan-2-ones, (B) l,3-dioxan-2-ones, (C) oxazolidin-2-ones, (D) l,3-oxazinan-2-ones, (E) 1,3,2-dioxathiolane 2-oxides, (F) l,3-oxathiolane-2-thiones. 

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