Radical-initiated reduction of five-or six-membered ring thiocarbonates, followed by alkaline hydrolysis, affords a convenient synthesis of 2-, 3-. 4-, and 5-deoxy-sugars. For 5,6-and 4.6-thiocarbonates the regiospecificity of the reaction complements the recently developed synthesis of 6-deoxy-sugars by ring opening of the same thiocarbonates with methyl iodide. Applications in the synthesis of 2-deoxy-~-ribose and 2'-deoxyadenosine are described.WE recently reported1 that the thiocarbonate ring in compounds like (1) was smoothly opened by treatment with methyl iodide to furnish a 6-deoxy-6-iodo-sugar. Reduction of the latter, suitably with the Cr2+-thiol reagent, followed by alkaline hydrolysis, gave a high yield of the 6-deoxy-sugar (2).We also recently developed3 the reduction of thiocarbonyl derivatives of secondary, but not primary, t Part 6, T.

The dynamics of the ZnCl4 anion in two compounds, one exhibiting a structural transition to an incommensurate phase (Rb2ZnCl4) and another not having any structural transition at all (Cs2ZnCl4), are studied through 35Cl NQR frequency ( nu ) and relaxation time (T1Q) measurements as a function of temperature T in their high-temperature (paraelectric) phases. Estimates of the potential barriers hindering the reorientational motions of ZnCl4 anions along axes parallel and perpendicular to the a axis of the crystal structure are obtained from the T1Q data. These results are analysed in conjunction with a qualitative comparison of relative mean square amplitudes of such motions obtainable from frequency data, in order to investigate the differences in the dynamics and structure of the ZnCl4 anion. There seems to be correlation between the dynamics of the anion in this phase and the possibility that the compound may exhibit a structural instability at low temperatures in this family.

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