Aldonic 1,5-lactone

Aldonic 1,4-lactone, III, 131 Aldonic 1,5-lactone, III, 130 Aldonic lactones, from aldonic phenyl-hydrazides, I, 22... 

Electroreduction of Aldonic Lactones M. Ya. Fioshin, I. A. Avrutskaya and E. V. Gromova, Itogi Nauki, Elektrokhim., 1968, 326-345. 

During the course of studies on the microbial production of chiral intermediates for D-pantothenic acid [2,134,135], Shimizu and co-workers found that several micro-organisms, such as Fusarium, Brevibacterium and so on, produce a novel enzyme that catalyzes the hydrolysis of aldonate lactones or aromatic lactones [136, 137],... 

Brevibacterium protophormiae produces a similar kind of lactonase, which hydrolyzes various kinds of aromatic lactones as well as the Fusaruim lactonase, but aldonate lactones are not hydrolyzed. The enzyme hydrolyzes only l-pantolactone D-pantolactone is not a substrate. The relative molecular mass of the native enzyme is 62 kDa, and the subunit molecular mass is 26.5 kDa [137],... 

An enzyme isolated from F. oxysporum catalyzes the hydrolysis of various aldonate and aromatic lactones (Table 19.1) (Shimizu et al, 1992). The hydrolysis of aldonate lactones proceeds stereospecifically through recognition of... 

Shimizu, S., Kataoka, M., Shimizu, K., Hirakata, M., Sakamoto, K., and Yamada, H. 1992. Purification and characterization of a novel lactonohydrolase, catalyzing the hydrolysis of aldonate lactones and aromatic lactones, from Fusarium oxysporum. Eur. J. Biochem.,209, 383-390. 

We found in our laboratory, a novel lactonohydrolase that catalyzes reversible hydrolysis of various lactones including aldonate lactones and aromatic lactones. The enzyme was crystallized from Fusarium oxysporum and characterized. It has been shown that the enzyme hydrolyzes only D-pantoyl lactone, a chiral intermediate for the commercial production of D-pantothenate, in a racemic mixture of pantoyl lactone and that the enzyme is very useful for the optical resolution of racemic pantoyl lactone (Fig. 3)7. When F. oxysporum mycelia entrapped in calcium alginate gel were incubated in 30% solution of DL-pantoyl lactone, almost stoichiometric hydrolysis of D-pantoyl lactone was observed. After repeated reactions for 150 times over 150 days, the mycelia retained more than 90% of their initial activity. A 1,000... 

The enantiomerically pure 2,3-unsaturated aldonic lactone 2 was prepared following Sharpless asymmetric dihydroxylation of 2-vinylfuran to give 1 (Scheme 1). The chain-extended aldonolactones 4 and 5 were prepared from the P-keto ester 3 by use of a diastereoselective reduction with either d- or L-tartaric acid in conjuction with sodium borohydride (Scheme 2). Reaction of Meldrum s acid (5a) with D-aldopentoses and hexoses gave 3,6-anhydro-2-deoxy-aldono-... 

The acetylated diazomethyl ketoses undergo the Wolff rearrangement (166) when treated in water with silver oxide to give a mixture of 2-deoxy-aldonic lactones (167). 

HCl + NaOH NaCl + H2O Aldonic lactone + H2O RCOOH RCOOH + NaOH -> RCOONa + H2O... 

Early applications of LiB H4 were commonly in the carbohydrate field, where it was used to selectively reduce aldonic lactones to give [l- H]aldoses. An example of such a reaction is the conversion of227to228 the reaction requires pyridine as solvent, in order to minimize further reaction to the corresponding [l- H2]alditol. 

Aldonic acids exist m equilibrium with their five or six membered lactones They can be isolated as carboxylate salts of their open chain forms on treatment with base... 

Like aldonic acids aldaric acids exist mainly as lactones... 

When a preparative method for an aldonic acid is re quired bromine oxidation is used The aldonic acid is formed as its lactone More properly described as a reaction of the anomeric hy droxyl group than of a free aldehyde... 

Oxidation to Sugar Acids and Lactones. When the aldehyde group of an aldose is oxidized, the resulting compound is an aldonic acid (salt form = aldonate) (11)4. Some aldonic acids are products of carbohydrate metaboHsm. 

Note D-Gluconic acid and other aldonic acids exist in equilibrium with lactone structures. 

Esters, lactones, lactams, acyl halides etc. are named by modifying the ending -ic acid as described for aldonic acids (2-Carb-20.2). 

A quantitative interpretation of aldonolactone inhibition in terms of an adaptation of the active site to a transition state approaching a planar, glycosyl oxocarbonium ion is made difficult for several reasons. Due to the interconversion between the 1,4- and 1,5-lactones, and their hydrolysis to the aldonic acids, their use is limited to kinetic studies with incubation times of 10 min or less. This was not realized by most investigators prior to 1970. In many cases, only the 1,4-lactone can be isolated its (partial) conversion into... 

The bromodeoxyaldonolactones have been used for the preparation of aminodeoxy aldonic acids and aminodeoxy sugars via azido derivatives (45,46). Likewise, a- and /J-aminopolyhydroxy acids have been prepared by treatment of the bromodeoxyaldonolactones with liquid ammonia (47). Thus, 3-amino-3-deoxy-D-threonic acid and 3-amino-3-deoxy-D-arabin-onic acid (40b) were obtained from 2-bromo-2-deoxy-L-threono- or D-xy-lono-1,4-lactone (38). It was shown that 2,3-epoxy carboxamides (namely, 39) are intermediates of the reaction. Heating at 90° for long periods led to the 3-amino-3-deoxyaldonamides, which upon acid hydrolysis yielded the corresponding aldonic acids. 

Aldono-1,5-lactones and free aldonic acids react with alcohols in the presence of hydrogen chloride to give the corresponding alkyl aldonates (84). The reaction is slower with 1,4-lactones. Because esterification takes place very slowly in the absence of an acidic catalyst, aldonic acids and their lactones may be recrystallized from boiling alcohols without appreciable esterification (85). However, in some instances, alkyl esters are formed under these conditions. For example, essentially pure ethyl L-mannonate was isolated (6.4% yield) from the mother liquors of crystallization L-man-nono-1,4-lactone, obtained by Kiliani synthesis from L-arabinose (86). Similarly, repeated recrystallization from ethanol of crude 2,3,4,6-tetra-O-acetyl-D-glucono- 1,5-lactone afforded the corresponding ethyl gluconate derivative (87). 

The acid-catalyzed acetalation of aldonolactones with alkyl acetals of aldehydes or ketones takes place, in some instances, with esterification of the lactone group to give acetal derivatives of alkyl aldonates (11,22). 

Addition of alcohols to lactones results in the formation of orthoacid or orthoester derivatives. Thus, reaction of lactone 95a with potassium cyanide in ethanol led to displacement of the tosyl group by cyanide and addition of ethanol to the lactone carbonyl group, to give the orthoacid derivative 95b, which was isolated as its acetate 95c. Mild deacylation of 95c led back to 95b, but under more vigorous reaction conditions the open-chain methyl aldon-ate was obtained (90). 

Aldonamides are readily prepared by reaction of lactones with liquid ammonia (86,99,100), with ammonium hydroxide (101,102), or by bubbling ammonia gas into alcoholic solutions of the sugar lactones (103-104). Aldonamides of the tetronic adds are stable in aqueous solution (105), but penton- or hexon-amides are hydrolyzed, as shown by the change of the optical rotation of the amide solutions (106). The hydrolysis is catalyzed by acids and bases, and the product was the ammonium salt of the aldonic acid. 

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