Gulono 4-lactone

In ketones existing largely as the enol, palladium may prove effective in minimizing hydrogenolysis, Hydrogen was added slereoselectively to the least hindered side of L-ascorbic add (3) to give L-gulono-1,4-lactone (4)... 

XIII. Biological Role of the Gulono-1,4-lactones and Gulonic Acids.320... 

The following article summarizes the methods of synthesis for L-gu-lono-1,4-lactone (1), D-gulono-1,4-lactone (2), and the corresponding... 

The most efficient synthesis of L-gulono-1,4-lactone (1) entails the reduction of D-glucofuranurono-6,3-lactone (7), which can be obtained from D-glucose2 (see Scheme 1). Catalytic hydrogenation3-4 of 7 in the presence of Raney nickel afforded 1 in 81% yield. Alternatively, D-... 

A short synthesis of D-gulono-1,4-lactone (2) from the inexpensive and readily available D-xylose (34) was first reported by Fischer and Stahel,18 and subsequently by others,12,25-31 and is shown in Scheme 6. The addition of hydrogen cyanide to D-xylose (34) resulted in the formation of cyanohydrins 35 and 36 which, on hydrolysis, afforded a mixture of D-gulonic acid (4) and D-idonic acid (37). D-Gulono-1,4-lactone may be obtained in 30-33% yield by recrystallization of the reaction products. In a similar way, L-xylose (l-34) has been converted32,33 in high yield into a mixture of L-gulonic and L-idonic acids. 

It has also been reported that D-galactose can be isomerized with molybdic acid to a mixture containing D-talose and D-gulose, but the yields are low.34-35 A number of derivatives of gulono-1,4-lactone have been prepared that, by reduction, would provide selectively protected derivatives of gulose. These derivatives will be discussed in subsequent Sections of this article. 

The crystal structure of D-gulono-1,4-lactone (2) has been determined,42 and is closely approximated by formula 38. Interestingly, the conformation of the side chain in 38 differs from that in crystalline L-ascorbic acid,1 very probably because of different steric interactions between the 3- and 5-hydroxyl groups in 2 (that is, 38) and 6. Bridgman43 measured the compressibility of gulono-1,4-lactone crystals. 

When L-gulono-1,4-lactone was treated with acetaldehyde diethyl acetal in N,N-dimethylformamide-benzene in the presence of a catalytic amount of p-toluenesulfonic acid, 5,6-O-ethylidene-L-gulono-1,4-lactone (54) was formed86 in 61% yield (40%, recrystallized). It is interesting that compound 54 was clearly a mixture of diastereo-... 

It was reported that, when L-gulono-1,4-lactone was treated with benzaldehyde and concentrated sulfuric acid, 2,6 3,5-di-0-benzyli-dene-L-gulono-1,4-lactone was formed.78,87... 

A number of triply protected derivatives of L-gulono-1,4-lactone (1) have been prepared. When 1 was treated with 3 equivalents of tert-butylchlorodimethylsilane, 2,5,6- and 3,5,6-tri-0-(tert-butyldi-methylsilyl)-L-gulono-l,4-lactone were formed86 in >90% yield. When 3,5-O-benzylidene-L-gulono-l,4-lactone was treated with chlorotriphenylmethane, 3,5-0-benzylidene-6-0-trityl-L-gulono-l,4-lactone was isolated in 38% yield.86... 

These structures are drawn to show their relationship to L-gulono- 1,4-lactone, rather than in the conventional fashion with C-6 at the left. 

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