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Synthesis, 1 H‐ and 13 C‐NMR spectra, crystal structure and ring openings of 1‐methyl‐6,9‐epoxy‐9‐aryl‐5,6,9,10‐tetrahydro‐1 H ‐imidazo [3,2‐ e ] [2 H ‐1,5] oxazocinium methanesulfonate
Author(s) -
Upadhyaya Subhash P.,
Davis Frank S.,
Lee Jae Jeong,
Zaw Kyaw,
Bauer Ludwig,
Heimer Norman E.
Publication year - 1997
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570340537
Subject(s) - chemistry , ring (chemistry) , aryl , methanesulfonic acid , crystal structure , hydroxymethyl , phenacyl , medicinal chemistry , nmr spectra database , stereochemistry , catalysis , crystallography , spectral line , organic chemistry , alkyl , physics , astronomy
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.