D-Glucono-1,5-lactones

Since KDG exists as a mixture of four species (a and (3 pyranose and a and p furanose forms) in equilibrium (figure 2) it was obviously an unsuitable material fcx the preparation of C-5 and C-4 modified analogs. We thus followed the same approach as that used for the preparation of KDG or for its 5-0-methyl methyl ester 2, starting from compounds 6 or 8 obtained in four or five steps respectively from commercially avalaible D-glucono-1,5-lactone (figure 3).2... 

Reaction of D-glucono-1,4-lactone with 2,2-dimethoxypropane-tin(II) chloride yields the 5,6-0-isopropylidene derivative 13, which on periodate oxidation afforded 2,3-0-isopropylidene-D-glyceraldehyde (21). However, the acid-catalyzed isopropylidenation of D-glucono-1,5-lactone with 2,2-dimethoxypropane afforded methyl 3,4 5,6-di-0-isopropylidene-D-gluco-nate (14) as the main product (22). Reduction of the ester function gave... 

D-Glucono-1,5-lactone has been transformed (23) into trihydroxycarbox-ylates bearing a long-chain alkyl acetal group (15a,b). The synthesis involves the acetalation of HO-4 and HO-6 with a long-chain alkyl carbonyl com-... 

Selective silylation of aldohexono-1,4-lactones with tert-butylchlorodi-methylsilane gave the 2,6-di-O-silylated derivatives as major products (40). However, D-glucono-1,5-lactone underwent ring-contraction during silylation to give 2,6-di-O-terl-butyldimethylsilyl-D-glucono-1,4-lactone (31a) together with its 5,6-di-O-silyl isomer (31b), in 65 and 18% yields, respectively. 

The stereocontrolled synthesis of a chiral, polyhydroxy 1,7-dioxa-spiro[5.5]undecene from 2,3,4,6-tetra-O-benzyl-D-glucono-1,5-lactone... 

Formylaminomethylenation of 2 3,5 6-di-O-isopropylidene-D-allono-1,4-lactone (80) gave the ( )alkene 90 in 59% yield. However, when the reaction was applied to the benzyl derivative of D-glucono-1,5-lactone (51a),... 

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). 

Condensation of D-glucono-1,5-lactone with 4 5-diamino-6-diethyla-mino-2-methylpyrimidine afforded the 8-polyhydroxyalkylpurine 101, a C-nucleoside of an open-chain sugar (118). Some other pyrimidines gave analogous products from either D-glucono- or D-ribono-lactones. 

D-Glucono-1,5-lactone reacted with aroylhydrazines (133) to give the corresponding l-aroyl-2-D-gluconylhydrazides (113), which underwent cy-clization upon heating with triethyl orthoformate, affording 5-aryl-2-eth-oxy-3-D-gluconyl-2,3-dihydro-1,3,4-oxadiazoles (114). 

Other heterocyclic compounds, precursors of C-nucleosides, were prepared by condensing D-glucono- 1,5-lactone with l-hydrazino-4-phen-... 

A one-pot, high-yielding synthesis of 1,2,3,4,6-penta-(9-acetyl-/ -D-( 1 -2H)glucopyranose (127) from tetra-O-acetyl-D-glucono-1,5-lactone (126) has been reported (172). Sodium borodeuteride reduction of 126, followed by in situ acetylation, gave the readily isolated and crystalline 127. The crystalline 2,4-dinitrophenyl 2,3,4,6-tetra-0-acetyl-/ -D-(l-2H)glucopyran-oside (128) was subsequently obtained from 127. 

Scheme 9 Acetalization of D-glncono-1,4-lactone and D-glucono-1,5-lactone with dodecanal or tetradecanal...

Scheme 21 Synthesis of L-aldoses from D-glucono-1,5-lactone...

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