P-D-fructofuranose

P-D-fructofuranose a-D-glucopyranose 1,2 2,1 -dianhydride a-D-fructofuranose a-D-glucopyranose 1,1 2,2 -dianhydride P-D-fructofuranose a-D-glucopyranose 1,1 2,2 -dianhydride P-D-fructopyranose a-D-glucopyranose 1,1 2.2 -dianhydride P-D-fructofuranose a-D-glucopyranose 2,1 3,2 -dianhydride P-D-fructopyranose a-D-sorbopyranose 1,2 2,1 -dianhydride P-D-fructopyranose a-L-sorbopyranose 1,2 2,1 -dianhydride di-a-L-sorbofuranose 1,2 2,3 -dianhydride a-l-sorbofuranose a-L-sorbopyranose 2,1 3,2 -dianhydride di-a-L-sorbopyranose 1,2 2,1 -dianhydride a-D-sorbopyranose a-L-sorbopyranose 1,2 2,1 -dianhydride di p-L-sorbopyranose 1,2 2,1 -dianhydride a-L-sorbopyranose p-L-sorbopyranose 1,2 2,1 -dianhydride a-L-sorbofuranose a-L-sorbopyranose l,2 2,l -dianhydride P-L-sorbofuranose a-L-sorbopyranose 1,2 2,1 -dianhydride a-L-sorbofuranose P-L-sorbofuranose l,2 2,l -dianhydride... 

O-p-D-Glucofuranosyl-a-D-fructofuranose p-D-fhictofuranose 1,2 2,1 -dianhydride (38) a-D-Fructofuranose 6 -0-a-D-glucopyranosyl-p-D-fructofuranose 1,2 2,1 -dianhydride (39) a-D-Fructofuranose 6 -0-p-D-fhictopyranosyl-P-D-fructofuranose 1,2 2,1 -dianhydride (40) 6-O-a-D-Glucopyranosyl-a-D-fructofuranose 6-O-a-D-glucopyranosyl-p-D-fructofuranose 1,2 2,1 -dianhydride (41)... 

Anhydro-a-D-fructofuranose P-D-fructopyranose l,2 2,l -dianhydride (55) 6-Deoxy-6-isothiocyanato-a-D-fructofuranose P-D-fructopyranose 1,2 2,1 -dianhydride (56) 6-Deoxy-6-iodo-a-D-fructofuranose 6-deoxy-6-iodo-p-D-fructofuranose 1,2 2,1 -dianhydride (57) 6-Chloro-6-deoxy-a-D-fructofuTanose 6-chloro-6-deoxy-P-D-fructofuranose 1,2 2,1 -dianhydride (58) 6-S-Heptyl-6-thio-a-D-fruclofuranose 6-S-heptyl-6-thio-p-D-fructofuranose 1,2 2,1 -dianhydride (59) 6-Azido-6-deoxy-a-D-fructofuranose 6-azido-6-deoxy-P-D-fructofuranose 1,2 2,l -dianhydride (60) 6-Amino-6-deoxy-a-D-fructofuranose 6-amino-6-deoxy-p-D-fructofuranose 1,2 2,1 -dianhydride (61) 6-Acetamido-6-deoxy-[Pg.260]

Anhydro-a-D-fructofuranose 6-deoxy-6-iodo-p-D-fructofuranose 1,2 2,l -dianhydride (63)... 

Deoxy-6-iodo-p-D-fructofuranose 6-deoxy-6-iodo-p-D-fructofuranose 1,2 2,3 -dianhydride (69) 6-Chloro-6-deoxy-P-D-fructofuranose 6-chloro-6-deoxy-p-D-ffuctofuranose 1,2 2,3 -dianhydride" (70)... 

This methodology was applied to the synthesis of L-streptose [91] and methyl a-D-mycaroside [95 a], The difficulty of this photochemical oxidation originates from the sensitivity of pyruvates to hydrolysis. This approach seems limited to small quantities of substrates but does not need any separation technique as in oxidation by pyridinium chlorochromate [95 b]. Nethertheless, photolysis of pyruvates of partially protected derivatives of a-D-g/ucofuranose and P-D-fructofuranose in benzene yields the corresponding oxidized products in excellent yields [96]. 

It is composed of two monosaccharides a-D-glucose (a -D-glucopyranose) and b -D-fructose (P -D-fructofuranose). 

P-O-Glucopyranose (Glup) p-D-Fructofuranose (Fruf) P-D-Galactopyranose (Galp)... 

The above methodology proved very successful for accessing pure standards of DFAs 5, 7, 10, and 14, which are among the most abundant DFAs in kinetic mixtures of diastereomers as well as in caramel. It is, however, intrinsically limited to compounds having identical ring size at both monosaccharide moieties. Moreover, the di-p-D-fructofuranose l,2 2,l -dianhydride isomer 12 remained elusive. 

Scheme 9 Stereoselective synthesis of di-D-fmctofuranose l,2 2,l -dianhydrides from 1,2-iso-propylidene-P-D-fructofuranose precursors by selective acidic activation in organic solvents...

The 0-3-0-3 distance is notably shorter in the p-D-fructofuranose p-o-fructo-pyranose l,2 2,l -dianhydride 13 than in the other three DFAs in this subset (Fig. 3). Its synthesis was accomplished by linking two o-fructopyranose moieties having different protecting group patterns with the o-xylylene bridge (40, Scheme 13). In one of those o-fructose residues pyranose furanose interconver-sion became possible after activation with TfOH ( 41). The higher reactivity of the five-membered ring towards spirocyclization led to the p,p-isomer with total selectivity in 41% yield [54]. 

Scheme 13 o-Xylylene-mediated synthesis of P-D-fructofuranose P-D-fructopyranose 1,2 2, 1 -dianhydride (13)... 

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