• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 112
  • 13
  • 13
  • 9
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 4
  • 2
  • 1
  • 1
  • Tagged with
  • 187
  • 187
  • 187
  • 41
  • 37
  • 35
  • 29
  • 16
  • 14
  • 13
  • 13
  • 12
  • 12
  • 11
  • 11
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The chemistry of benzophosphole derivatives /

Nwe, Khin Than January 1974 (has links)
No description available.
2

Diels-Alder reactions of 1,4-diaryl-2,3-naphthaquinones

Aung, Oo. January 1974 (has links)
No description available.
3

Synthesis of polysubstituted pyridines : Diels-Alder addition of 1-AZA-1, 3-dienes with acetylenic and ethylenic dienophil

Steizer, Lindsay S. January 1986 (has links)
The synthesis of methyl 3,6-dimethylpyridine-2-carboxylate (192) by the Diels-Alder addition of 3-butene-2-one dimethylhydrazone (190) and methyl-2-butynoate (16) is described. The structure of 192 was confirmed by the synthesis of methyl 2,6-dimethylpyridine-3-carboxylate (195), the opposite regioisomer.The synthesis of methyl 3,5-dimethylpyridine-2-carboxylate (199) from [4+2] cycloaddition of 2-methyl-2-propenal dimethylhydrazone (171) and 16 is described. In addition to producing a small amount of 199 directly, the reaction produced an intermediate of possible structure 198 which yielded 199 on catalytic dehydrogenation.On prolonged heating, 2-acetyl-5-methylpyridine (200) was produced by the reaction of diene 171 with methyl vinyl ketone (176).The preparation of 2-cyan-5-methylpyridine (201) from the tetrahydropyridine derivative 175 via catalytic dehydrogenation is described.The synthesis of 5,7-dioxo-3-methyl-6-phenyl-1,1.,5,6,7-pentahydropyrroloC3,1.-b] pyridine (202) through the Diels-Alder addition of diene 171 and N-phenylmaleimide (149) is described. Also reported is the preparation of 5,7-dioxo-3-methyl-6-phenyl-3,5,6-trihydropyrrolo [3,1+-b]pyridine (203) via dehydrogenation of 202. / Department of Chemistry
4

An approach to carbocyclic analogues of C-nucleosides.

Reader, Grant William. January 1973 (has links)
No description available.
5

The steroelectivity of chiral allenes in the dielsalder reaction

Herring, Laura Elizabeth 12 1900 (has links)
No description available.
6

Regiochemistry and stereochemistry of the Diels-Alder reaction; the synthesis and reactions of 1,3-cyclohexadienes

Duckwall, Louis Ralph 12 1900 (has links)
No description available.
7

Synthetic studies towards gelsemine

Bainbridge, Jeremy D. E. January 1997 (has links)
No description available.
8

Conformational effects in the photochemistry of tetrahydro-1,4-naphthoquinones

Jennings, Barry Michael January 1975 (has links)
The photochemistry of a variety of tetrahydro-1,4-naphthoquinones (structure 1) has been investigated. These were synthesized by Diels-Alder reaction of corresponding p-quinones and acyclic-1,3-dienes [diagram omitted]. Three substituent-dependent types of reactions were observed: (1) for adducts possessing hydrogen substituents at C₄a and C₈a (bridgehead position), the prevalent process was one of abstraction of a β-hydrogen atom from C₅(or equivalently, C₈) by excited carbonyl oxygen. In general, three product types were then observed, derived from carbon-carbon bond formation (proceeded in two instances by conformational rotation about the C₄a - C₈a bond) in the bisallylic radical so produced. Placing a methyl or phenyl substituent at C₂ renders the β-hydrogens non-equivalent, and abstraction occurs in accord with expectations based on the formation of the more stable biradical intermediate. In adducts possessing bridgehead substituents, rotation about the C₄a - C₈a bond in the biradical is suppressed and only a single product type (enone alcohol) is formed, which possesses the same relative conformation as the biradical and starting adduct. In the case where the bridgehead substituents are carboxymethyl, however, secondary photolysis in benzene solution occurs, giving rise to a product where the bridgehead substituents are nearly eclipsed. (2) For the adduct possessing exo-methyl substituents at positions 5 and 8 as well as methyls at the bridgehead positions and at and C₂ and C₃, hydrogen abstraction was partially suppressed in favor of a process tentatively concluded to involve Ύ~hydrogen abstraction by excited enone carbon, giving rise to a product, the formation of which again requires little conformational change in the biradical. (3) For adducts possessing endo-methyl substituents at C₅ and C₈ as well as bridgehead substituents, a novel oxetane product was observed, formally the result of a cycloaddition reaction involving the remote double bond and one of the carbonyl groups. The oxetane derived from the duroquinone adduct was found to be photolabile, giving back starting material and, eventually, a quantitative conversion to a novel cage diketone. The reactivity differences for these systems, as well as for those previously studied in our laboratory, are interpreted as being due to the effects of substituents on the energy barrier to conformational isomerization in the biradical intermediates. Finally, the potential utility of these photochemical reactions for the synthesis of unusual ring systems is noted. / Science, Faculty of / Chemistry, Department of / Graduate
9

The chemistry of 1-propene-1,3-sultone and related homochiral sultams : their preparation, chemical transformations and applications in asymmetric Diels-Alder reactions

Jiang, La Sheng 01 January 1998 (has links)
No description available.
10

A self replicating reaction and a new approach to ionophore selection

Wang, Bing January 1996 (has links)
No description available.

Page generated in 0.1354 seconds