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Diastereo isomeric erythro and threo forms of 2,3-epoxy-1 -phenylphospholane 1-oxides were synthesized from l-phenyl-2-phospholene 1-oxide using 30% hydrogen peroxide with NaOH. The selectivity of the diastereo isomers was depended on reaction time and concentration of peroxide and base, and kind of solvents, which controlled the selectivity of the eyrthro and threo forms. Introduction Phospha sugar is one of sugar analogs that have a phosphorous atom in place of the ring oxygen atom of normal sugars. Recently, several nucleoside derivatives of sugars, e.g., AZT (1) and Ribavim (2), are prepared and used as antivirus agents (1,2). In addition to the nucleoside of normal sugars, sugar modified novel nucleoside derivatives of pseudo sugars or hetero sugars such as aza(3), carba(4), and thia-sugars (5) have been synthesized and reported. In the present work, we deal with the successful preparative method for formation of the epoxide of 2-phospholene 1-oxide derivatives. 2,3-Epoxy-l-phenylphospholane 1-oxide is an anhydro type phospha sugar derivative and a potential precursor for phospha sugar derivatives. In our laboratory, an efficient method for the stereospecific epoxidation of 2-phospholenes using sodium peroxide as a reagent was developed to make the corresponding epoxide such as 2,3-epoxy-l-phenylphospholane 1-oxide (6). Instead of using sodium peroxide, using 30% hydrogen peroxide and base are less expensive, less harmful to the environment, less dangerous for handling, and more practical than the previous method. The new method of synthesizing diastereo isomeric erythro and threo forms of 2,3-epoxy-l-phenylphospholane 1-oxides was optimized using hydrogen peroxide with base by different experimental conditions. Results and Discussion Scheme 1 shows the epoxidation of l-phenyl-2-phosopholene 1-oxide (1) to prepare 2,3-epoxy-l-phenylphospholane 1-oxidc (2). The reaction afforded the diastcrcomcric epoxide mixture of erythro 2a, which was the major product, and threo 2b. 295 Unauthenticated Download Date | 6/2/19 6:48 PM Vol. 10, Nos. 4-5, 2004 Diastereo isomeric erythro and threo forms of 2,3-epoxy-1-phenvlphospholane 1-oxides synthesized by an action of hydrogen peroxide Spectral data of 2a and 2b were taken by 'H-NMR and C-NMR. The preparation method and NMR data are reported in later experimental section.

heterocyclic communications

DIASTEREO ISOMERIC erythro AND threo FORMS OF 2,3-EPOXY-1-PHENYLPHOSPHOLANE 1-OXIDES SYNTHESIZED BY AN ACTION OF HYDROGEN PEROXIDE WITH BASE ON 1-PHENYL-2-PHOSPHOLENE 1-OXIDE