By the use of the N-iodosuccinimide (NW-procedure, various glycals could be converted into 2-deoxy-2-iodoglycosyl phosphates. Treatment of glycals 1 and 7 with NIS and dibenzyl phosphate gave the corresponding a-1,2-tram-diaxial 2-deoxy-2-iodoglycosyl phosphates 2 and 8 as the main products. The /3-1,2-tram-diequatorial compounds 3 and 9 were isolated as by-products. Analogous reaction of glycals 4 and 10 gave the corresponding 2-deoxy-2-iodoglycosyyl phosphates 5, 6, 11, and 12 as crude products, which were characterized by 'H NMR spectroscopy. Classical phosphorylation of 2-deoxyglycosyl chlorides 14 and 16 with silver dibenzyl phosphate gave the corresponding dibenzyl Zdeoxy-aglycosyl phosphates 15 and 17. Alternatively, glycosylation of tri-0-acetyl-o-glucal (1) using dibenzyl phosphate and triphenylphosphine hydrobromide afforded 15 in lower yield. The application of S-(Zdeoxyglycosyl) phosphorodithioates as glycosyl donors provided the most convenient way to dibenzyl 2-deoxyglycosyl phosphates. The a-glycosyl phosphates 15,20, and 22 could be synthesized by reaction of the 2-deoxyglycosyl dithiophosphates 18, 19, and 21 with dibenzyl phosphate and activation by iodonium di-sym-collidine perchlorate. Similary, the 2,6-dideoxyglycosyl dithiophosphates 23 and 25 gave the 2,6-dideoxy phosphates 24 and 26; however, the isolation of these labile compounds could not be effected.
INTRODUmION
Glycosyl phosphates are important intermediates in a variety of biosynthetic processes such as in sugar nucleotide metabolism'. Selective deoxygenation in the sugar moieties gives rise to compounds of close structural analogy to natural derivatives, which may serve as enzyme inhibitors or substrate analogs. The synthesis of several 3-, 4-, or 6-deoxyglycosyl phosphates as precursors to the corresponding sugar nucleotides has previously been 'developed*. However, due to their hydrolytic instabilitiy, the synthesis of 2-deoxyglycosyl phosphates remained difficult and was not satisfactorily achieved3. The only alternative approach to the synthesis of 2-deoxy-cY-D-glycopyranosyl phosphates appeared to be enzymatic