title: Cyclization of the substituted N-(ortho-cyclopropylphenyl)-N'-aryl ureas and thioureas in the gas phase and solution.
abstract: Electron ionization (EI), chemical ionization (CI), tandem mass spectrometry, high-resolution measurements, and labeling studies as well as quantum chemical calculations were used to understand the behavior of the molecular radical cations (EI) and protonated molecules (CI) of substituted N-(ortho-cyclopropylphenyl)-N'-aryl ureas and N-(ortho-cyclopropylphenyl)-N'-aryl thioureas in a mass spectrometer. Fragmentation schemes and possible mechanisms of primary isomerization were proposed. According to the fragmentation pattern, formation of the corresponding benzoxazines and benzothiazines was considered as the major process of isomerization of the original M(+.) and MH(+), although some portions of these ions definitely transformed into other structures. The treatment of N-(ortho-cyclopropylphenyl)-N'-phenyl urea and N-(ortho-cyclopropylphenyl)-N'-phenylthiourea in solution with strong acids formed predicted 4-ethyl-N-phenyl-4H-3,1-benzoxazin-2-amin and 4-ethyl-N-phenyl-4H-3,1-benzothiazin-2-amine as principal products.
authors.affiliation: Department of Chemistry, Laboratory of Physical Organic Chemsitry, Moscow State University, Leninskie Gory, 119992 Moscow, Russia.
authors.forename: Vladislav V
authors.initials: VV
authors.lastname: Lobodin
authors.forename: Alexandr N
authors.initials: AN
authors.lastname: Fedotov
authors.forename: Piotr I
authors.initials: PI
authors.lastname: Dem'yanov
authors.forename: Albert T
authors.initials: AT
authors.lastname: Lebedev
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Ovcharenko
authors.forename: Kalevi
authors.initials: K
authors.lastname: Pihlaja
authors.forename: Tom
authors.initials: T
authors.lastname: Blumenthal
mesh_terms: D000465:Algorithms; D002849:Chromatography, Gas / Q000379:methods*; D005740:Gases / Q000032:analysis / Q000737:chemistry; D044367:Phase Transition; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013890:Thiourea / Q000032:analysis* / Q000737:chemistry*; D014508:Urea / Q000032:analysis* / Q000737:chemistry*
chemical_list: D005740:Gases; D012996:Solutions; D014508:Urea; D013890:Thiourea