Synthesis of vicinal monoamino-dideoxysugars

Abstract

Sunzinavy Sequential treatment of methyl 3,4-O-isopropylidene-P-L-erythro-pentopyranosidulose (I) with aqueous NaOH and phenylhydrazine results in elimination of acetone and formation of 2-S-methoxytetrahydropyran-3,4-dione 4-phenylhydrazone (111) , which has been con-verted into a 3-amino-3,4-dideoxypentose; and similarly, a 3-amino-3,4,6-trideoxyhexose has been obtained starting with methyl 6-deoxy-3,4-O-isopropylidene-cc-~-lyxo-hexopyranosidulose (11).

Synthesis of 3-amino-3,4-dideoxysugars

“…Solvents were evaporated under reduced pressure and the residual diethyl acetal was extracted with deuteriochloroform. The filtered extract showed the folIowing characteristics: 8,, 1 1 g) was dissolved in ethanol (5 ml) and aqueous sodium hydroxide (10%; 0.05 ml) was added. After 1 h at room temperature the reaction mixture was neutralised [ion exchange resin IR-l20(H+)] and concentrated to leave a solid residue (60 mg) which was identified as 3-hydroxy-2-methyl-4H-pyran-4-one (maltol) (1 7).…”

“…Normally, an O-isopropylidene acetal is formed when diol protection is needed under basic conditions, but it is known that nearby electron-withdrawing substituents can influence the stability of such acetals. Elimination of the isopropylidene group from compound (1) was demonstrated by boiling the pentopyranosidulose in ethanolic sodium hydroxide and trapping the evolved vapour in 2,4dinitrophenylhydrazine reagent. Acetone 2,4-dinitrophenylhydrazone was isolated.…”

“…The extract was shaken with charcoal, dried, and filtered through a short alumina column. Concentration of the filtrate gave crystals of thequinoxaline derivative of 2S-methoxytetrahydropyran-3,4-dione (10) (b) The pentopyranosid-2-ulose (1) (1 g) was dissolved in hot ethanol (6 ml), the solution was cooled, and aqueous sodium hydroxide ( 2 . 5 ~; 0.5 ml) was added After 30 sec, phenylhydrazine (0.5 ml) was added and the mixture was boiled vigorously for 2 min.…”