I. Generation and mechanistic study of t-butyl exo-methylene-substituted 2,3-dimethylene-2,3-dihydrofurans and a thiophene analogue. II. Generation and study of the dimerization of alkyl ring-substituted 2,3-dimethylene-2,3-dihydrofurans. III. Diels-alder reaction of 2,3-dimethylene-2,3-dihydrofuran and o-xylylene. IV. Formation of the 2,5-dimethylene-2,5-dihydrothiophene trimer and its synthetic application
In Section I, the generation and a mechanistic study of t-butyl exo-methylene-substituted 2,3-dimethylene-2,3-dihydrofurans and a thiophene analogue are reported. The results not only unambiguously support the previous proposed two-step mechanism for the dimerization of 2,3-dimethylene-2,3-dihydrofuran (1), they also provide them with two of the most unreactive o-quinodimethanes, namely, 2-methylene-3-t-butylmethylene-2,3-dihydrofuran (2), and 2,3-di-t-butylmethylene-2,3-dihydrofuran. In Section II, the preparation and the dimerization of a series of alkyl ring-substituted and carbomethoxy ring-substituted derivatives of 1 are presented. This study concludes that bulky alkyl substituents on the ring of furan monomers do not promote the (4 + 2) dimerization process. In Section III, a Diels-Alder reaction of 1 and its two deuterated analogues with methyl acrylate reveals the presence of a secondary deuterium isotope effect which strongly supports a stepwise mechanism. This conclusion is further strengthened by the fact that the Diels-Alder reaction of 1 with cis dienophiles proceeds non-stereospecifically. A comparison study of o-xylylene with dienophiles reaches the same conclusion. In Section IV, a convenient synthesis of cyclooctadecane from the thiophene trimer of 2,5-dimethylene-2,5-dihydrothiophene is described. This synthesis offers an efficient alternative to existing routes.
- Research Organization:
- Iowa State Univ. of Science and Technology, Ames (USA)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 5571944
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALKENES
DIELS-ALDER REACTION
DEUTERIUM
ISOTOPE EFFECTS
FURANS
DIMERIZATION
THIOPHENE
CHEMICAL PREPARATION
CHEMICAL REACTIONS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
POLYMERIZATION
STABLE ISOTOPES
SYNTHESIS
400201* - Chemical & Physicochemical Properties
400202 - Isotope Effects
Isotope Exchange
& Isotope Separation