Galactono-1,4-lactone

Scheme 3 Synthesis of L-galactono-1,5-lactones from 2,4-hexadienoates...

A cluster of modest to abundant fragment ions reflecting the ST head group (i.e., 3-sulfogalactosyl moiety) at m/z 259, 257, and 241 is present [18]. The m/z 259 and miz 257 ions may represent the galactose 3-sulfate and galactono-1,5-lactone 3-sulfate anions [3]. Further loss of a water molecule from m/z 259 leads to the ion at m/z 241,... 

Two new routes to L-ascorbic acid (58) have been described. In one of these, L-galactono-lactone (57) is the precursor, convertible in three steps (Scheme 10) into ascorbic acid, whilst in the other (Scheme 11), the 1,5-anhydro-D-galactitol 59, accessible from D-galactose, was used as an intermediate.73... 

Loupy and colleagues have prepared acetals of 1-galactono-l,4-lactone in excellent yields [31] by adsorbing the lactone and the aldehyde on montmorillonite K 10 or KSF clay followed by exposing the reaction mixture to microwave irradiation (Scheme 6.1). 

Scheme 6.1 Formation of acetal derivatives of 1-galactono-l, 4-lactone.

Acetals of L-galactono-1,4-lactone (an abundant byproduct of the sugar beet industry) have thermotropic liquid crystalline properties. Acetalization in DMF containing H2S04 in the presence of anhydrous CuS04 gave (after 12 to 24 h at 40 °C) yields of 20-35% (Scheme 8.27). 

The major pathway probably proceeds via D-galacturonic acid and L-galactono-1,4-lactone, as these are converted to L-ascorbic acid by mitochondria prepared from peas and mung beans, but neither L-gulono-1,4-... 

A partially acetylated galactonolactone, namely, 2,3,6-tri-O-acetyl-D-ga-lactono-1,4-lactone (30b), was obtained by an indirect method. Tritylation and further acetylation of D-galactono-1,4-lactone gave 2,3,5-tri-O-acetyl-... 

Similarly, compound 73 was prepared from a persilylated D-galactono-1,4-lactone precursor in 60-80% yield (71). However, when unpurified Tebbe s reagent was employed, 1,4-lactones (for example 71a) gave a mixture of 72a and the product (74) of hydration of the double bond. The... 

This enzyme [EC 1.1.1.48] catalyzes the reaction of d-galactose with NAD+ to produce o-galactono-l,4-lactone and NADH. 

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