Sucrose epoxides

SCHEME 23. Some of the novel derivatives of sucrose derived from the 2,3-manno-sucrose epoxide by Hough, Richardson, Gurjar, and Sincharoenkul (1986). 

R. Khan, M. R. Jenner, H. Lindseth, K. S. Mufti, and G. Patel, Ring-opening reactions of sucrose epoxides Synthesis of 4 -derivatives of sucrose, Carbohydr. Res., 162 (1987) 199-207. 

The value of sugar epoxides as synthetic intermediates is well-known in carbohydrate chemistry. Synthesis of sucrose epoxides hitherto has not been repor-... 

The solvent also plays an important role in the success of the reaction. In general, reaction in benzene or toluene gives higher yields of inverted products. - Although pyridine is not suitable in the preparation of nucleotides, pyridine can be used for the synthesis of sucrose epoxide, and a mixture of dioxane-pyridine (9 1) can be utilized in the preparation of sugar carboxylates. Mixed solvent systems may be necessary when the acid and alcohol components have widely differing solubilities. Thus a mixture of HMPA and dichloromethane works well in the synthesis of lipophilic carbohydrate esters such as cord factor. ... 

Sulfonate Esters. Sucrose sulfonates are valuable intermediates for the synthesis of epoxides and derivatives containing halogens, nitrogen, and sulfur. In addition, the sulfonation reaction has been used to determine the relative reactivity of the hydroxyl groups in sucrose. The general order of reactivity in sucrose toward the esterification reaction is OH-6 OH-6 > OH-1 > HO-2. 

The latter reaction set up the possibility of making such exotic derivatives as 2,3-anhydro-4-chloro-talo-sucrose (Scheme 13) by a four-step sequence involving O-mesylation of 3,6,l, 3, 4, 6 -hexa-0-pivaloylsucrose, high-temperature LiCl displacement, O-depivaloylation with concomitant epoxide formation, and finally O-acetylation. 

SCHEME 22. A new pathway to the 2,3-manno-epoxide derivative of sucrose (1986). 

As compared to the esterification of sucrose, cataly tic etherification of sucrose provides another family of non-ionic surfactants that are much more robust than sucrose esters in the presence of water. Synthesis of sucroethers can be achieved according to two processes (1) the ring opening of epoxide in the presence of a basic catalyst and (2) the telomerization of butadiene with sucrose using a palladium-phosphine catalyst. 

Many papers from the patent literature on pyrethroids and juvenile hormones cannot be included in this Report. Papers have reported the synthesis and activity of monoterpenoid juvenoids, including geranyl pyridyl ethers " and geranyl alkyl ethers and amines and their epoxides. Further papers in this section include a report of the potent lung toxicity of perillaketone, the observation that the malodorous water contaminant 2-methylisoborneol has the l-R-exo configuration, and that fenchyl methyl L-aspartylaminomalonate is 2 x 10" times sweeter than sucrose. ... 

The reaction of sucrose 2,3-manno-epoxide with potassium thioacetate and ammonium chloride in aqueous ethanol gave the expected 3-5>-acetyl-3-thio-altropyranoside (101). Treatment of 6,6,-dibromo-6,6,-dideoxysucrose hexaacetate with potassium thioacetate and A/, Ak dimethyl thiocarbamate gave the corresponding derivatives of 6,6,-dithiosucrose. The air oxidation of 6,6,-dithiolsucrose gave the bridged 6,6,-episulfide. A detailed conformational study of sucrose 6,6,-dithiol and sucrose 6,6 -episulfide revealed that they are similar but distinguishable (102). 

The carboxymethylation of sucrose can be achieved by reaction with sodium chloroacetate in water or water-2-propanol mixtures in basic medium. In this case, a similar regioselectivity is observed as for the reaction with epoxides or alkyl halides with major substitutions at secondary positions, notably at OH-2.80 Cyanoethylated sucrose derivatives and the corresponding carboxylated compounds were also prepared.81... 

Treatment of free sucrose with phthalimide under Mitsunobu conditions affords modified derivatives in which the primary 6-OH and 6 -OH groups are replaced by a phthalimido moiety, with concomitant epoxide formation at C-3 and C-4 (Scheme 19).253 Chloro-anhydro derivatives were formed similarly under Mitsunobu conditions in the presence of zinc chloride.254... 

Finally, a valuable example of multistep modifications of sucrose is the synthesis of Sucralose (l Ab -trideoxy-l Ab -trichloro-tya/flcm-sucrose)—a compound 650 times more sweeter than sucrose,15,326,327 which was obtained by treatment of 6-O-acetylsucrose with sulfuryl chloride in pyridine. Further reaction of this derivative with triphenylphosphine and diethyl azodicarboxylate afforded an epoxide from which a tetrachloro-derivative... 

The Mitsunobu conditions, applied without any carboxylic acid, were shown to provide anhydro (3, 4 -epoxide)284 286 and dianhydro sucrose derivatives.331 Some of these compounds were further transformed by reduction (leading to dehydrosucroses) or ring-opening leading to sucrose epimers and dehydrohalo-or amino sucroses (see also Scheme 7).332... 

Scheme 44. Amphiphilic sucrose ethers from epoxides.

R. D. Guthrie, I. D. Jenkins, and R. Yamasaki, Epoxidation with triphenylphosphine and diethyl azodicarboxylate Epoxide derivatives of sucrose, Carbohydr. Res., 85 (1980) C5-C6. 

Reaction of the artificial sweetener sucralose (being 650 times sweeter than sucrose) with triphenylphosphine and diethyl azodicarboxylate afforded epoxide 102 from which the tetra-chloro-derivative 103 was obtained (O Fig. 25) [72]. 

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