Epoxides azodicarboxylate

Phenols and primary alcohols form ethers when heated with dicyclohexylcarbo-diimide606 (see 0 22). 1,2-Diols can be converted to epoxides by treatment with dimethylformamide dimethyl acetal [(MeO CHNMej],607 with diethyl azodicarboxylate [EtOOCN=NCOOEt] and Pl P,608 with a dialkoxytriphenylphosphorane,609 or with TsCl-NaOH-PhCH2NEt3+ Cl.610... 

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... 

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. 

Diols are directly converted into oxiranes with Ph3P or other phosphines in the presence of diisopropyl azodicarboxylate (Mitsunobu reaction). Simple alkenes can be converted into nonracemic epoxides in high yields and with excellent ee values via a two-step sequence of asymmetric dihydroxylation and Mitsunobu cyclodehydration of the intermediate diol (Scheme 18) <20010L2513>. These reactions give best results using electron-poor alkenes . 

EPOXIDES N-Bromosnccinimide. Di-methylsulfonium methylide. Potassium r-butoxide. Triphenylphosphine-Diethyl azodicarboxylate. 

Guthrie, R D, Jenkins, I D, Yamasaki, R, Skelton, B W, White, A H, Epoxidations with triphenylphosphine and diethyl azodicarboxylate. Part 1. Synthesis of methyl 3,4-anhydro-D-tagatofuranosides, J. Chem. Soc., Perkin. Trans 1, 2328-2334, 1981. 

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]. 

Reaction of adenosine with triphenylphosphine and diethyl azodicarboxylate gave the 2, 3 -phosphorane (105) and not the 3, 5 -phosphorane as previously reported (Mitsunobu et ai, Chem. letters, 1974, 1473). The structure was confirmed from H" and P n.m.r. measurements. With aradmo-adenosine the 2, 3 -/yxo-epoxide (106) was obtained in near quantitative yield xylo-adenosine also gave (106) but much more slowly and in only 60% yield. ... 

PhaP - phthalimide - diisopropyl azodicarboxylate) were used to convert sucrose selectively into the di- or tri-phthalimido-taqato-epoxides (42) and (43), by reaction for 2.5 or 48 hours, respectively. Each of these products was isolated in 70% yield by... 

An even sweeter chlorodeoxysucrose was later synthesized by the reaction of sucralose with triphenylphosphine and diethyl azodicarboxylate to give the 3, 4 -lyxo epoxide, followed by stereospecific opening of the epoxide with chloride to... 

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