From Unsaturated Sugars

2-Acetamido-2-deoxy-a-D-talopyranosides of serine and two hexose derivatives, e.g. 23, were synthesized from tetra-O-benzoyl-2-hydroxy-D-galactal 21 via 

Reagents i. pnSe—Jj BU4NF ii, HS(CH2)3SH, EtaN, NaBH4 iii, AC2O, Pv 

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Scheme 8 Radicals from unsaturated sugar lactones.22...

At C-2 position, carbohydrate radicals were formed starting from unsaturated sugars by acetoxymercuration followed by reduction of the carbon-mercury bond... 

The carbocycles substituted at the double bond (with for example, an alkox)methylene group) can also be prepared from the appropriately functionalized unsaturated sugars. Synthesis of a-glucosidase inhibitor—valienamine—was realized from unsaturated sugar chirons as shown in Fig. 9 [86]. 

Synthesis of yd-Lactams from Unsaturated Sugars and Isocyanates... 

From Unsaturated Sugars. — Allylic rearrangement of ally cyanates, formed in situ from carbamates such as 24 (derived originally from o-glucal triacetate), yielded isocyanates, e.g. 25, that could then be converted to allylic amine derivatives, e.g. 26 (Scheme 6). Trapping of an allylic... 

Some syntheses of useful chiral cyclopentane derivatives have been reported this year. For example, (69) has been obtained from (-)-quinic acid, and the hexa-acetate (70) from unsaturated sugar derivatives. The diene (71), of 36% optical purity, results from a thermal hetero-ene reaction of a chiral allene aldehyde. Gill and Rickards have reported full details for the resolution of the cyclopentenone (72), derived from phenol. °... 

A 2,4,6-trideoxy-6-iodo-hexose derivative prepared from D-glucose also with potential as a chiral intermediate for synthesizing inhibitors of this enzyme is mentioned in Chapters 7 and 11. The synthesis of spirobis-1,4-dioxans from 2-chloroethyl fructopyran-oside is mentioned in Chapter 3 (ref.6), and the formation of tricyclic pyrone derivatives from unsaturated sugars is referred to in Chapter 12 (ref.31). 

Lespieau, R., Synthesis of Hexitols and Pentitols from Unsaturated Poly-hydric Alcohols, II, 107-118 Levi, Irving, and Purves, Clifford B., The Structure and Configuration of Sucrose (oipta-D-Glucopyranosyl beta-D-Fructofuranoside), IV, 1-35 Liggett, R. W., and Deitz, Victor R., Color and Turbidity of Sugar Products, IX, 247-284... 

Fig. 35 Unsaturated sugar lactones obtained from monosaccharides.

The association between Drs. Fletcher and Pravdic, which started when she was a Visiting Scientist at the Institute in Bethesda, continued after she returned to Yugoslavia. Together they investigated the chemistry of unsaturated 2-acetamido-2-deoxy-D-glucose derivatives, and, with Emmanuel Zissis, the preparation of lactones from these sugars, work stemming from Dr. Fletcher s interest in Tay-... 

An interesting procedure has been developed by Vat le to obtain C-5 branched-chain sugars [189]. It also takes advantage of the stereospecificity of the Claisen rearrangement of allyl (vinylsulfinyl) ether 158 derived from a 4,5-unsaturated sugar. An acrylic derivative 159 is formed in the process by elimination of sulfenic acid (Scheme 53). 

I. Pelyvas, T. Liudhorst, and J. Thiem, En route to thromboxane compounds from carbohydrates, I. Synthesis of the unsaturated sugar precursors, Liebigs Ann. Chem. p. 761 (1990). 

A. Carbocycles from unsaturated halo sugars by hex-5-enyl... 

A. Carbocycles from Unsaturated Halo Sugars by Hex-5-enyl Radical Cyclizatlon [8]... 

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