Sugar 0-thioformates

In a recent report Hungarian workers found that sugar-derived thioformates undergo cycloadditions thermally or under high pressure (2.5 kbar).29 In general, high pressure reactions showed better facial selectivity than did thermal ones. An example is shown in Eq. (12). 

For starting, we have chosen dithiooxalates and O-thioformates as dienophiles (11). Both types of compounds have been used for Diels-Alder reactions before (12, 13) but, to our knowledge, no attempt has been made to apply them to chiral substrates. Sugar dithiooxalates 6 and 8 as well as thioformates 9 and 10 have been prepared by known methods (14,15) (Figure 4.)... 

Figure 7. Hetero Diels-Alder reactions of sugar O-thioformates.

A new mild reaction for the deoxygenation of secondary alcohols has been applied successfully to sugars the reaction, which is radical in character, involves the reduction of a thiobenzoate with tributylstannane (see Scheme 25). Other references to the use of thioesters and the photochemical transformation of dithiobis(thioformates) into thiols are reported in Chapter II, the reaction of cyclic thiocarbonates with methyl iodide to give tu-iodo-iS-methyl thiocarbonates... 

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