SYNTHESIS, H-1-NMR AND C-13-NMR SPECTRA, CRYSTAL-STRUCTURE AND RING OPENINGS OF 10-TETRAHYDRO-1H-IMIDAZO[3,2-E][2H-1,5]OXAZOCINIUM METHANESULFONATE

The methanesulfonic acid catalyzed reaction of 1-(4-chloro- and dichlo rophenyl)-2-(1-methyl-2-imidazolyl)ethanones 1a and 1b with glycerol p roduced cis-and imidazolyl)methyl]-4-hydroxymethyl}-1,3-dioxolanes and 2a and 2b with a 2:1 cis/trans ratio. Besides these five-membered ket als, the reaction of la with glycerol afforded a small amount of -chlo rophenyl)-2-[(1-methyl-2-imidazolyl)methyl]-5 -hydroxy}-1,3-dioxane (3 a, 7%). The reaction of methanesulfonyl chloride with cis-2 formed the corresponding methanesulfonates, cis-4, which rapidly cyclized to the title compounds 5. Base-catalyzed ring opening of 5 furnished 1-methy l-5,6-dihydro-6-hydroxymethyl-8-(4-chloro- and -dichlorophenyl)-1H-imi dazo[3,2-d][1,4]oxazepinium methanesulfonates 7. Acid-catalyzed hydrol yses of 5 or 7 provided 1-methyl-2-[(4-chloro- and 2,4-dichloro)phenac yl] -3-[(2,3-dihydroxy)-1-propyl]imidazolium salts 12. Structure proof s were based on extensive H-1 and C-13 chemical shifts and coupling co nstants and structures of 3a and 5a were confirmed by single crystal X -ray crystallography.