13C magnetic resonance studies 70. The behavior of bicyclo[2.2.2]octenone under strongly basic conditions. A competition between retro Diels–Alder and Haller-Bauer-cleavages

1977 ◽  
Vol 55 (24) ◽  
pp. 4184-4190 ◽  
Author(s):  
A. K. Cheng ◽  
J. B. Stothers
Keyword(s):  
Magnetic Resonance ◽  
Diels Alder ◽  
Claisen Condensation ◽  
Magnetic Resonance Studies ◽  
Phenolic Components ◽  
Bicyclic Ketones ◽  
Major Reaction

As a test for possible competitive α- and β-enolization in bicyclic ketones the behavior of bicyclo[2.2.2]octenone in t-BuO−–t-BuOH at 185 °C has been examined. The major reaction (∼90%) involves Claisen condensation followed by retro Diels-Alder elimination of ethylene and Haller–Bauer cleavage. All acidic and phenolic components, accounting for 90% of the product, have been identified and characterized, primarily by their 13Cmr spectra.

1H and 13C nuclear magnetic resonance studies on the Diels–Alder adducts of isoquinolin-3(2H)-ones

1985 ◽  
Vol 63 (5) ◽  
pp. 1001-1004 ◽  
Author(s):  
Gâbor Tóth ◽  
Attila Almásy ◽  
László Hazai ◽  
Antal Schnitta ◽  
Gyula Devák
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Diels Alder ◽  
Spectral Parameters ◽  
Magnetic Resonance Studies ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

The stereochemistry of the adducts of isoquinolin-3(2H)-ones and maleimides was studied and 1H and 13C spectral parameters of the endo and exo stereoisomers were determined. The predominant rotamers generated by rotation about the C(7)—C(7a) and (C1)—C(1′) bonds were identified.

13C magnetic resonance studies. 124. Preparative ring expansions of bicyclic ketones by homoketonization of cyclopropoxide analogs

1986 ◽  
Vol 64 (7) ◽  
pp. 1390-1399 ◽  
Author(s):  
Vijay Patel ◽  
Arthur J. Ragauskas ◽  
J. B. Stothers
Keyword(s):  
Magnetic Resonance ◽  
Ring Expansion ◽  
Synthetic Method ◽  
Expansion Process ◽  
Enol Ethers ◽  
Magnetic Resonance Studies ◽  
Silyl Ethers ◽  
Silyl Enol Ethers ◽  
Ring Expansions ◽  
Bicyclic Ketones

Homoketonization of some readily prepared cyclopropoxides provides a new synthetic method for ring expansion of the [2.2.1] and [2.2.2] ring systems. Cyclopropanation of the trimethylsilyl enol ethers derived from a variety of polycyclic ketones affords the required cyclopropyl silyl ethers, which may be ketonized directly or hydrolyzed to the corresponding cyclopropanols before ketonization. The results for fourteen examples serve to define the scope of the ring expansion process, and the silyl enol ethers, cyclopropyl silyl ethers, and most of the corresponding cyclopropanols have been characterized by 13Cmr. The stereochemistry of the ketonization leading to ring expansion has been established by deuterium labelling experiments.

Fluorine magnetic resonance studies. VII. Fluorine-fluorine coupling over five bonds in 1-Fluoro-2-(2'-fluorophenyl)ethanes

1984 ◽  
Vol 37 (8) ◽  
pp. 1769 ◽  
Author(s):  
DA Burgess ◽  
MF Finn ◽  
D Jordan ◽  
ID Rae ◽  
D Walters
Keyword(s):  
Magnetic Resonance ◽  
Diels Alder ◽  
Spin Coupling ◽  
Side Chain ◽  
Magnetic Resonance Studies ◽  
Close Proximity ◽  
New Compounds ◽  
Spin Spin Coupling ◽  
Alder Adduct

Spin-spin coupling between an aromatic fluorine and fluorines in an adjacent side chain (Ar-C-C-F), with J values in the range 2-5 Hz, is reported for four new compounds. The coupling probably arises from through-space interactions taking place when rotation of the side chain brings the two types of fluorine into close proximity. In a Diels-Alder adduct of fluoranil and 1-fluoro-4-methyl- anthracene, this proximity is denied the fluorines and no coupling is observed.

C Nuclear Magnetic Resonance Studies. Part 48. C Spectra of a Variety of Bicyclic Ketones

1975 ◽  
Vol 53 (18) ◽  
pp. 2808-2808
Author(s):  
S. H. Grover ◽  
D. H. Marr ◽  
J. B. Stothers ◽  
C. T. Tan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Studies ◽  
Bicyclic Ketones ◽  
Nuclear Magnetic

not available

13C Nuclear Magnetic Resonance Studies. Part 48. 13C Spectra of a Variety of Bicyclic Ketones

1975 ◽  
Vol 53 (9) ◽  
pp. 1351-1361 ◽  
Author(s):  
S. H. Grover ◽  
D. H. Marr ◽  
J. B. Stothers ◽  
C. T. Tan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Important Influence ◽  
Magnetic Resonance Studies ◽  
Methyl Substitution ◽  
13C Nuclear Magnetic Resonance ◽  
Bicyclic Ketones ◽  
Methyl Derivatives ◽  
Derivatives Of ◽  
Nuclear Magnetic

The 13C n.m.r. spectra of a series of 37 bicyclic ketones have been recorded to examine the variations in 13C shieldings with structure and with methyl substitution. Several examples of six skeletal types were included: bicyclo[4.4.0]decanones, bicyclo[4.1.0]heptanones, bicyclo-[3.1.0]hexanones, bicyclo[3.2.2]nonanones, bicyclo[3.2.1]- and -[3.3.0]octanones as well as bicyclo[2.1.1]hexan-2-one, nopinone (6,6-dimethylbicyclo[3.1.1]heptan-2-one), and two methyl derivatives of the latter. The observed trends associated with methyl substitution follow well-defined patterns and offer further support for the application of 13C shieldings as aids for stereochemical assignments especially through the well known γ effects. The variation in the shieldings of the carbonyl carbons in these systems suggested that bond eclipsing interactions have an important influence on this parameter. With this notion, the heretofore puzzling variations observed for the cycloalkanones are readily interprétable in terms of their favored conformations.

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