Synthesis of 3-amino-3,4-dideoxysugars

Abstract

Sequential treatment of methyl 3,4-O-isopropylidencp-L-erythro-pentopyranosidulose (1 ) with aqueous sodium hydroxide and phenylhydrazine results in elimination of acetone and formation of 2s-methoxytetrahydropyran-3,4-dione 4-phenylhydrazone (7) as the main product. Similarly, methyl 6-deoxy-3,4-0-isopropylidene-2-t-lyxo-hexopyranosid -2 -u lose (2) was converted into 2Rmethoxy -6smethyltetrahydropyran -3,4-dione 4-phenylhydrazone (8). The effect of base on the related uloside, methyl 6-deoxy-2,3-O-isopropylidene-a-L-lyxo-hexopyranosid-4-ulose (1 6), resulted in the formation of 3-hydroxy-2-methyl-4H-py~an-4-one (maltol) (1 7). Compounds (7) and (8) have been converted into, respectively, 3-amino-3,4-dideoxy-~-erythro-pentopyranose (22) and 3-amino-3,4,6-trideoxy-~ribo-hexopyranose (25).Methyl glycosiduloses have been used extensively as intermediates in the modification of sugars. Such modification is usua1.l~ at the site of the hydroxy group in a methyl glycoside at which oxidation has been effected to produce the glycosidulose. In this paper, details are provided of a sequence of reactions which results in modification at C-3 and C-4 of a methyl glycopyranosid-2-ulose derivative.' This reaction sequence provides a convenient route for the preparation of aminosugars containing the -CH2CHNH2system, as occurs in some antibiotics.2The 2-ulosides investigated in this work were methyl 3,4-O-isopropylidene-~-~-er~t~r~-pentopyranos~duIose (1) and methyl 6-deoxy-3,4-0-isopropylidene-a-~-f~~xo-hexopyranoid-2-dose (2) which were prepared in good yields by well established procedures from, respectively, L-arabinose and ~-fucose.~ I H A 1 1 ) R 1 = R 2 = H J R 3 = O M e , X = O Configuration a t C-3-C-4, L-erythro 2 1 R' = Me , R2 = OMe , R3 = H X = 0 Configuration a t C-3-C-4, D-erythro ( 3 ) R' = R2 = H , R3 = OMe, X = NNHPhAtom numbering of the compounds in this paper is based on nome:nclature and the 'H n.rn.r. data