NOVEL OBSERVATIONS ON THIOPHOSPHORYL-GROUP TRANSFER IN SUGAR BETA-HYDROXY PHOSPHORODITHIOATE SYSTEMS - SYNTHESIS AND X-RAY MOLECULAR-STRUCTURE OF -EPITHIO-2-O-(P-TOLYLSULFONYL)-BETA-D-ALLOPYRANOSE

The reaction of hydro-2-O-(p-tolylsulfonyl)-beta-D-galactopyranose 6 w ith the triethyl-ammonium salt of 2-mercapto-5,5-dimethyl-1,3,2-dioxap hosphorinane 2-sulfide 7' gives the hitherto unknown -epithio-2-O-(p-t olylsulfonyl)-beta-D-allopyranose 8 in high yield. The intermediates i n this reaction are: yl)-4-thio-2-(p-tolysulfonyl)-beta-D-glucopyranos e 9 and -4-thio-2-O-(p-tolylsulfonyl)-beta-D-glucopyranose 10. The for mer can be obtained by addition of 2-mercapto-5,5-dimethyl-1,3,2-dioxa phosphorinane 2-sulfide 7 to the dianhydro sugar 6. Formation of the l atter was confirmed by P-31 NMR Spectroscopy. Comparative conformation al studies of dianhydro compound 6 and of episulfide 8 were undertaken . They revealed that, despite the opposite orientation of the epoxy an d epithio groups, the overall conformation of 5- and 6-membered rings remains the same. The absolute configuration of compound 6 has been de terminedas 1R,2R,3S,4S,5R, and of compound 8 as 1R,2S,3S,4R,5R.