Methyl D-arabino-hex-2-ulopyranosonate as a building block for spiro[1,4-benzoxazine-2,2 '-pyrans]

A novel glycosyl donor, methyl (3,4,5-tri-O-acetyl-beta-D-arabino-hex-2-ulo pyranosyl)onate bromide, obtained in two steps from methyl beta-D-arabino-h ex-2-ulopyranosonate, was converted into its cl-nitrophenyl glycoside, whic h in turn was reductively cyclized to form acetylated benzoxazinoid spirans . Deprotection led to (2S)-3',4,4',5'-tetrahydroxy-D-arabino-2H-1,4-benzoxa zin-2-spiro-2'-pyran-3(4H)-one and (2S)-3',4',5'-trihydroxy-D-arabino-2H-1, 4-benzoxazin-2-spiro-2'-pyran-3(4H)-one. Analogous compounds are prepared f rom 5-methoxy-2-nitrophenol. The new class of spiro functionalized carbohyd rates is structurally related to natural benzoxazinone acetal glucosides. T he assignment of configuration and conformation of all products was based o n H-1 NMR H,H coupling constants and optical rotation values. (C) 1999 Else vier Science Ltd. All rights reserved.