Aldonolactones reaction with

The use of aldonolactones in synthesis has been extensively reviewed, concerning among other topics O-substitution, deoxygenation, reaction with... 

Condensation of the corresponding aldonolactone derivative with 1,1,1-tri-chlorotoluene and trimethyl phosphite gives the exo-alkenes 166 from which C-glycosides are available. Reaction of 0-substituted 1,2-0-isopropylidene-a-D-xylofuranose with allyltrimethylsilane and a Lewis add gives the 2-0-un-protected p-C-allyl C-glycosides. ... 

An extensive review on the use of aldonolactones in synthesis has appeared, covering amongst other topics O-subsdtation, deoxygenation, reaction with nucleophiles, p-eliminadons, and the use of aldonolactones in preparing other classes of contpounds such as iminoalditols. ... 

Per-benzoylated aldonolactones undergo a reductive elimination reaction with samarium diiodide leading to unsaturated derivatives (Scheme 3). Deoxygenation at the 2-position can also take place. The difference in the reductive elimination patterns between the D-g/uco and D-galacto isomers may be due to the axial disposition of the OBz in the galacto isomer. 

The diastereoselective transformation of various 3-deoxy-aldonolactones by reaction with terpene ketones in the presence of samarium diiodide into derivatives such as 24 or 25 has been reported. The same authors have also reported similar work using simpler ketones. ... 

The transformation of aldonolactones into the corresponding dichloromethylene derivatives on reaction with triphenylphosphine-carbon tetrachloride reagent has been described (Scheme 10). This reagent is of more general applicability than the bis(dimethylamino)phosphine-carbon tetrachloride reported earlier (Vol. 18, p.34). Ester carbonyl groups are also dichloromethylated. 

A route to l,5-dideoxy-l,5-imino-D-xylonolactam has utilized a 5-azido-5-deoxy-aldehydo-T>-xylose derivative,and a route to C-glycosides by reaction of aldonolactone derivatives with alkyl lithiums followed by triethylsilane reduction is elaborated in Chapter 3. 

Addition of lithiated heterocycles to aldonolactones yields carbon-linked nucleosides (56). Thus, the reaction of 2,3 5,6-di-O-isopropylidene-L-gu-lono-1,4-lactone (9b) or 2,3-O-isopropylidene-D-ribono-l,4-lactone (16a) with various lithiated heterocycles gave gulofuranosyl derivatives 53a-g or ribofuranosyl derivatives 54b,c. Gulonolactols 53a-g and ribonolactols 54b,c were acetylated with acetic anhydride in pyridine to yield their acetyl derivatives. The stereochemistry of compounds 53a-g and 54b,c was discussed in terms of the Cotton effect of circular-dichroism curves of the ring-opened alcohols formed upon reduction by sodium borohydride. The configuration at C-l of 53g was proved by means of X-ray analysis (57,58). 

The application of lithiumtrimethylsilyl acetate for the C-l elongation of aldonolactones has been examined (73). Although the reagent had been successfully used for the alkenation of lactone carbonyl groups (74), in the case of aldonolactones 10b or 25b only insignificant yields of the alkenes, but 30 - 40% of the lactols 49a or 50a, were obtained (73). However, these lactols, alternatively prepared in good yields by a Reformatsky-type reaction (53,54), were readily eliminated to the desired alkenes by simple treatment with methanesulfonyl chloride-triethylamine at 0°. Thus, from 49a or 50a separable E,Z mixtures (76a and 76b, or 77a and 77b, respectively) were obtained in good yields (73). 

VI. Reaction of Aldonolactones with Alcohols 1. Formation of Esters... 

VII. Reaction of Aldonolactones with Ammonia and Related Nucleophiles... 

Sugar lactones react readily with hydrazine to give crystalline derivatives useful for isolation and identification (127). Thus, addition of hydrazine to a reaction mixture containing an aldonolactone facilitates isolation of the product. The lactone may be regenerated from the hydrazide by treatment with nitrous acid (128). The phenylhydrazides obtained on treatment of aldonolactones with phenylhydrazine are also useful for characterization (129,130). 

C-Glycosyl compounds are important molecular targets as they occur in Nature and have interesting biological properties (for reviews on C-glycosylation, see [72-75]). Chain extensions of aldonolactones have been employed to create C-C bond formation at the anomeric center. Claisen-type reactions of aldono-1,4-lactones (e.g., 9, 55) with acetone or acetophenone (Scheme 17) generate hemi-acetals of type 56a-c [76]. Similarly, lactone 55b reacts with CHsCN/NaH to give hemiacetal 57. 

Another method for the alkylidenation of aldonolactones uses addition of organ-ometallic reagents [78]. For example, Lin et al. [85] described an efficient route to conjugated anomeric dienes or aldehydes based on the reaction of aldono-1,4- and aldono-1,5-lactones (1, 62) with allylmagnesium chloride (Scheme 19), giving allyl hemiacetals (e.g., 63a, b). Hemiacetal can be dehydrated [e.g., with (CF3C0)20] to produce dienes 64a, b, or ozonolyzed (e.g., to give 65). 

---