Abstract
The methanesulfonic acid catalyzed reaction of 1‐(4‐chloro‐ and 2,4‐dichlorophenyl)‐2‐(1‐methyl‐2‐imida‐zolyl)ethanones 1a and 1b with glycerol produced cis‐ and trans‐{2‐haloaryl‐2‐[(1‐methyl‐2‐imidazolyl)methyl]‐4‐hydroxymethyl}‐1,3‐dioxolanes 2a and 2b with a 2:1 cis/trans ratio. Besides these five‐membered ketals, the reaction of 1a with glycerol afforded a small amount of trans‐{2‐(4‐chlorophenyl)‐2‐[(1‐methyl‐2‐imidazolyl)methyl]‐5‐hydroxy}‐1,3‐dioxane (3a, 7%). The reaction of methanesulfonyl chloride with cis‐1 formed the corresponding methanesulfonates, cis‐4, which rapidly cyclized to the title compounds 5. Base‐catalyzed ring opening of 5 furnished 1‐methyl‐5,6‐dihydro‐6‐hydroxymethyl‐8‐(4‐chloro‐ and 2,4‐dichlorophenyl)‐1__H__‐imidazo[3,2‐d][1,4]oxazepinium methanesulfonates 7. Acid‐catalyzed hydrolyses of 5 or 7 provided 1‐methyl‐2‐[(4‐chloro‐ and 2,4‐dichloro)phenacyl]‐3‐[(2,3‐dihydroxy)‐1‐propyl]imidazolium salts 12. Structure proofs were based on extensive ^1^H and ^13^C chemical shifts and coupling constants and structures of 3a and 5a were confirmed by single crystal X‐ray crystallography.