Gulose derivatives, synthesis

A highly diastereoselective 1,3-dipolar cycloaddition of a nitrone employing the sultam auxiliary has been used in the synthesis of 215, a major metabolite of nicotine <04T9997>. i-gulose-derived nitrone 212, upon treatment with a, P-unsaturated sultam (25)-213, undergoes 1,3-dipolar cyeloaddition to afford the isoxazolidine 214 with high endo stereoselectivity, which is further elaborated to hydroxycotinine (-i-)-215. 

L-Gulose derivatives suitable for use in the synthesis of bleomycin have been obtained via 6-hydrazone derivatives of 6-aldehydo-D-... 

An application of the Rh-catalyzed hydroboration in the functionalization of a cyclic substrate was reported by Roger in the synthesis of the glycopeptide bleomycin A (99, Scheme 7.17) [38]. The exocyclic olefin in 97 underwent hydroboration to give the i-gulose derivative 98 in 82% yield and 98 2 dr. 

Minster and Hecht16 reported a synthesis of a derivative of L-gulose (9) from D-glucose (25) that takes advantage of the ready availability of... 

L-Gulose, required for synthetic work associated with bleomycin, has been prepared by a new route from D-glucose (Scheme 2). A new synthesis of D-arabinose from D-glucose involves periodate oxidation of the glucose derivative (3) (Scheme 3). The reaction is thought to be general for all aldoses that form 1,2-0-isopropylidene derivatives. ... 

A method of more general application depends on the reduction of iodo derivatives in which the iodine has replaced the hydroxyl of a primary alcoholic group. These are easily obtained by treatment of the tosyl derivatives with sodium iodide in acetone solution (sealed tube) or in refluxing acetonyl-acetone 228) or acetic anhydride 229). The reduction is often carried out by catalytic methods. The 5-deoxy-n-xylose is synthesized from D-xylose by this method, and by application of the cyanohydrin synthesis 6-deoxy-n-gulose is prepared 230). 

Aldotetrose B must be D-threose because the alditol derived from it (o-threitol) is optically active (the alditol from D-erythrose, the other possible D-aldotetrose, would be meso). Due to rotational symmetry, however, the alditol from B (D-threitol) would produce only two NMR signals. Compounds A-F are thus in the family of aldoses stemming from D-threose. Since reduction of aldopentose A produces an optically inactive alditol, A must be D-xylose. The two diastereomeric aldohexoses C and D produced from A by a Kiliani-Fischer synthesis must therefore be D-idose and D-gulose, respectively. E and F are the alditols derived from C and D, respectively. Alditol E would produce only three C NMR signals due to rotational symmetry while F would produce six signals. 

The synthesis, structures and function of caibohydiate-metal coordination conqmunds has beoi reviewed. Conqilexes of some hepurfiiranose derivatives containing primary-secondary 1,3-diol moieties with molybdenum tetraacetate have been studied and their CD spectra have allowed assignment of die configurations (rf the secondary alcohol centres. Aldoses of the arabino- and xylo- series have been shown to form tetradentate acyclic complexes with molybdare ions in aqueous acidic media, and the structure and conformation of molybdare conqil ces with S-deoxy-L-arabinose and S-deoxy-L-ribose have been studied. Molybdate complexes of D-allose, D-altrose, D-gulose and D-idose have been studied by NMR methods. ... 

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