Preparation and Cycloaddition Reactions of Oxazoline Nitrogen Oxides
Ashburn, Stephen Patrick
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/70288
Description
Title
Preparation and Cycloaddition Reactions of Oxazoline Nitrogen Oxides
Author(s)
Ashburn, Stephen Patrick
Issue Date
1985
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Organic
Abstract
Oxazoline N-oxides have been prepared in medium to high yields under mild conditions by condensation of 2-(hydroxyamino)-2-methyl-1-propanol with ortho esters or amide acetals. 3 + 2 Cycloaddition reactions of the oxazoline N-oxides and the related pyrroline N-oxides with phenyl isocyanate, dimethyl acetylenedicarboxylate, methyl phenylpropiolate, phenylpropiolonitrile, methyl acrylate, and acrylonitrile were carried out. The reaction of 4,4-dimethyl-2-phenyloxazoline N-oxide with acetylenic dipolarophiles in concentrated solutions of dimethylamine hydrochloride in dichloromethane, however, led to the formation of isoxazoles. Competitive experiments demonstrated that 2,4,4-trimethyloxazoline N-oxide is at least 6,800 times more reactive toward phenyl isocyanate than the analogous 2,5,5-trimethylpyrroline N-oxide, and is 160 times more reactive toward dimethyl acetylenedicarboxylate than the pyrroline N-oxide. Rate constants for the 3 + 2 cycloaddition reactions of 4,4-dimethyl-2-phenyloxazoline N-oxide and 5,5-dimethyl-2-phenylpyrroline N-oxide with phenyl isocyanate and dimethyl acetylenedicarboxylate were measured. These data indicate that the oxazoline N-oxide is approximately 76,000 times more reactive toward phenyl isocyanate than the pyrroline N-oxide, and is 70 times more reactive toward dimethyl acetylenedicarboxylate than the pyrroline N-oxide. An explanation for the enhanced reactivity of oxazoline N-oxides is forwarded on the basis of frontier molecular orbital theory.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
