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A new synthetic route to 4-Deoxy-hexoses of both L- and D-series, prepared in good yields from noncarbohydrate starting products are reported. The most common approach to the preparation of 4-deoxy-hexoses consists of the deoxygenation at C-4 of natural hexoses.

A study was conducted to characterize the design and synthesis of 3-C-lithiated (5,6-dihydro-1,4-dithiin-2-yl)((4-methoxybenzyl)oxy)methane that can be used as an allylic alcohol anion equivalent. The parent compound was determined in four steps to produce an overall yield of 83% while the coupling reactions were found to be affected by BuLi treatment and miscellaneous electrophiles. Results indicated that the double bond can be functionalized even in a stereocontrolled fashion.

A novel route is developed for 2' ,3' -dideoxy-[beta]-L-erythro-hexopyranosyl nucleosides equipped with a 1' -([N.sup.6]-benzolyadenin-9-yl) or a 1' -(thymin-1-yl) moiety. The synthesis of the enantiopure sugar moiety is performed by a de novo approach based on a domino reaction as the main step and N-glycosylation is analyzed by either nucleobase-transfer mechanism or in situ anomerization.

An efficient and general de novo synthetic route to enantiomerically pure L-hexoses is achieved starting from the heterocyclic homologating agent 5,6-dihydro-1,4-dithiin-2-yl[(4-methoxybenzyl)oxy]methane and methyl [alpha],[beta]-isopropylidene-L-glycerate. The sugar scaffold is constructed by an acid-catalyzed domino reaction, which has enabled selective preparation of either methyl 2,3-dideoxy-[alpha]-L-threo-hex-2-enopyranosides or 1,6-anhydro-2,3-dideoxy-[beta]-L-threo-hex-2-enopyranose as key intermediates.

The synthesis of 1,6-anhydro-[beta]-L-hexopyranosyl derivatives are described for the preparation of L-sugars. The studies have shown that as 1,6-anhydro derivatives are obtained, dithioethylene bridge removal and double-bond dihydroxylation has given access to protected L-allose and L-glucose in stereoselective fashion and high yields.

The reaction of the singlet oxygen with various sulfur-containing cyclic alkenes is discussed. The interaction has been found to be extremely useful for the dye-sensitized photooxygenation of 5,6-dihydro-1,4-dithiins.

An expeditious and efficient synthesis of 1,6-anhydro-β-L-hexopyranosyl derivatives 3 as valuable building blocks for the preparation of L-sugars is herein reported. This route relies upon the use of a domino reaction involving five synthetic steps from the 5,6-dihydro-1,4-dithiin 4. As 1,6-anhydro derivatives 3 are obtained, dithioethylene bridge removal and double-bond dihydroxylation give access to protected L-allose and L-glucose in stereoselective fashion and high yields. [ABSTRACT FROM AUTHOR]

A novel route to 2',3'-dideoxy-β-l-erythro-hexopyranosyl nucleosides equipped with a 1'-(N(6)-benzoyladenin-9-yl) or a 1'-(thymin-1-yl) moiety has been developed. Synthesis of the enantiopure sugar moiety was carried out by a de novo approach based on a domino reaction as the key step. N-Glycosidation was explored via either nucleobase-transfer mechanism (B = T) or in situ anomerization (B = A or T), affording target nucleosides with high overall stereoselectivity.