Carbohydrate 5-lactones

Carbohydrate lactones have been used as the carbonyl reagent in the Reformatsky reaction. Thus, 2,3 5,6-di-O-cyclohexylidene-D-mannono-1,4-lactone [44, obtained by oxidation of the mannofuranose derivative (49)] reacted with ethyl bromoacetate and zinc to give the protected 2-deoxy-3-octulosonic acid ethyl ester (45a) in 69% yield (50). Ketonic hydrolysis with potassium hydroxide in aqueous methanol, followed by acidification and heating, afforded the 1-deoxyheptulose derivative 45b. Similarly, starting from compound 44, the 1-C-substituted allyl and propar-gyl lactols were prepared on reaction with allyl or propaigyl bromides in the presence of zinc (51). 

Lundt I (2003) Iminosugars, isoiminosugars, and carbasugars from activated carbohydrate lactones efficient synthesis of biologically important compounds. In Witzak ZJ, Tatsuta K (eds) Carbohydrate synthons in natural products chemistry synthesis, functionalization and applications. ACS Symposium Series, vol 841. American Chemical Society, Washington, DC,pp 117-140... 

Recently, Williams et al. have reported the ring-opening polymerization of carbohydrate lactones [43, 44] and the lactide polymerization coinitiated by carbohydrate esters and pyranoses [45] (Scheme 4). 

E. J. Enholm and S. Jiang, Highly stereoselective coupling of carbohydrate lactones with terpene ketones promoted by SmI2, Tetrahedron Lett. 55 6069 (1993). 

E. J. Enholm, S. Jiang, and K. Abboud, Branched-chain carbohydrate lactones from a samar-ium(U) iodide promoted serial deoxygenation-carbonyl addition reaction, J. Org. Chem. 58 4061 (1993). 

Yu. A. Zhdanov, Yu. E. Alekseev, T. P. Sudareva, and V. M. Khar kovskii, Aminolysis of carbohydrate lactones and esters a simple path to nitrogen-containing carbohydrate compounds and their precursors, Zh. Obshch. Khim. (Russ.), 62 (1992) 2587-2592. 

Iminosugars, Isoiminosugars, and Carbasugars from Activated Carbohydrate Lactones Efficient Synthesis of Biologically Important Compounds... 

Sulikowski s total synthesis of urdamycinone B [36] (Scheme 12.45) is characterized by C-glycosidation of a carbohydrate lactone and Diels-Alder reaction of a C-glycosyl... 

The diastereoselective reduction of hemiacetals derived from isopropylidene derivatives of carbohydrate lactones is depicted in Scheme 2. Diastereomeric ratios ranged from 86 14 to 100 1 (major epimer only shown in the Scheme). ... 

Fig. 35. Preparation of suitable glycosynthons for polymer synthesis from carbohydrate lactones.

The first direct olefination of carbohydrate lactones was discovered using the tris(dimethylamino)phosphine-carbon tetrachloride couple which reacted at low temperature to yield dichloroolefins in excellent yields (Scheme 1). The reaction was limited to certain lactones in particular those having a dioxolane protecting group at 0-2-0-3. This limitation was later bypassed by using triphenylphosphine which is less reactive but reacts at higher temperature allowing reaction with poorly reactive 8-lactones. ... 

In the meantime, the Wittig olefination of carbohydrate lactones with stabilized phosphoranes at high temperature was discovered. This was an efficient reaction which worked with y- and 5- lactones in excellent yields. This way another new class of exo-glycals 3 was available, as Z/E mixtures but with an interesting push-pull substitution of the double bond (Scheme 1). ... 

In Scheme 4.16 is depicted another reduction reaction, involving carbohydrate lactones, which are converted into the corresponding 2-deoxylactones by reaction with samarium diiodide in a water-THF mixture (Hanessian and Girard, 1994). The best amount of water for obtaining the hydroxyketone was 1-2% of total volume. More water led to significant amounts of benzaldehyde (Hasegawa et al, 1996). 

Carbohydrate lactones, e.g., compound (42), added TMSCHjLi and TMSCHClLi to form... 

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