13C nuclear magnetic resonance studies. 114. An examination of the [3.3.1.0] → [4.3.0.0] rearrangement via β-enolization and H/D exchange in tricyclic ketones

1985 ◽  
Vol 63 (6) ◽  
pp. 1250-1257 ◽  
Author(s):  
Arthur J. Ragauskas ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Ring Expansion ◽  
Butyl Alcohol ◽  
Deuterium Incorporation ◽  
Magnetic Resonance Studies ◽  
Endo Isomer ◽  
Exchange Processes ◽  
Tert Butyl Alcohol ◽  
13C Nuclear Magnetic Resonance

The behavior of the exo and endo isomers of 7,7-dimethyltricyclo[3.3.1.02,4]nonan-6-one (5, 6) under strongly basic conditions (t-BuOH/t-BuOH/185 °C) has been examined. In sharp contrast to their [3.2.1.02,4] analogs, the endo isomer is stable while the exo readily rearranges to 8,8-dimethyltricyclo-[4.3.0.02,4]nonan-7-one (16). Experiments were carried out in tert-butyl alcohol-O-d1 to establish the sites of deuterium incorporation in the initial ketones as well as the relative rates and stereoselectivities of the exchange processes. Ketones 5 and 6 were prepared through ring expansion by ketonization of cyclopropoxides generated from the [3.2.1.0] homologs; the stereochemistry of these ketonizations was established by 2H labelling.

Nuclear magnetic resonance studies. XL. Tricyclooctanone rearrangement, [3.2.1.0] → [3.3.0.0], via γ-enolization and a 2Hmr study of H/D exchange in tricyclic ketones

1984 ◽  
Vol 62 (7) ◽  
pp. 1385-1391 ◽  
Author(s):  
A. K. Cheng ◽  
Ashim K. Ghosh ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Membered Ring ◽  
Deuterium Incorporation ◽  
Magnetic Resonance Studies ◽  
Endo Isomer ◽  
Exchange Processes ◽  
Initial Transformation ◽  
Nuclear Magnetic

The effect of strongly basic conditions (t-BuO−/t-BuOH/185 °C) on the exo and endo isomers of 7,7-dimethyltri-cyclo[3.2.1.02.4]octan-6-one has been examined. While the exo isomer is stable, the endo isomer readily rearranges to 4,4-dimethyltricyclo[3.3.0.02.8]octan-3-one (6) which subsequently undergoes reduction of the three-membered ring. The initial transformation is one of very few examples of γ-enolate rearrangement. Experiments in tert-buiyl alcohol-O-d1 were carried out to establish the several sites of deuterium incorporation in the initial ketones and in 6 using 2Hmr. These results reveal the stereochemistry of γ-enolate formation and cleavage as well as the stereoselectivities and relative rates of the exchange processes.

13C magnetic resonance studies. 138. An examination of the [3.2.2.0] → [4.2.1.0] rearrangement via β-enolization and H/D exchange in tricyclic ketones

1989 ◽  
Vol 67 (2) ◽  
pp. 187-192
Author(s):  
Sriyawathie Peiris ◽  
J. B. Stothers ◽  
Shirley E. Thomas
Keyword(s):  
Magnetic Resonance ◽  
Butyl Alcohol ◽  
Rearrangement Product ◽  
Methylene Carbon ◽  
Deuterium Incorporation ◽  
Magnetic Resonance Studies ◽  
Endo Isomer ◽  
Tert Butyl ◽  
Tert Butyl Alcohol

The behavior of the endo and exo isomers of 7,7-dimethyltricyclo[3.2.2.02,4]nonan-6-one (9, 17) under strongly basic conditions (t-BuO−/t-BuOH/185 °C) has been examined. In both cases rearrangement to the corresponding 8,8-dimethyl-tricyclo[4.2.1.02,4]nonan-7-one (11, 18) was found, with the exo isomer reacting approximately 8 times faster. Experiments in tert-butyl alcohol-O-d1 were carried out to determine the specific sites, the relative rates, and the stereochemistry of deuterium incorporation in the initial ketones. Although H/D exchange occurs most readily at the cyclopropyl methylene carbon in the endo isomer, none of the rearrangement product expected to arise via γ-enolate formation was observed. The results for these ketones are compared with our earlier observations in the related [2.2.2], [3.2.1.0], and [3.3.1.0] systems. Keywords: homoenolization, tricyclic ketones, H/D exchange.

Nuclear Magnetic Resonance Studies. XXVII. Homoenolization of Fenchone. A Mechanistic Study Utilizing C And H Nuclear Magnetic Resonance

1975 ◽  
Vol 53 (2) ◽  
pp. 212-223 ◽  
Author(s):  
A. L. Johnson ◽  
J. B. Stothers ◽  
C. T. Tan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Deuterium Exchange ◽  
Mechanistic Study ◽  
Deuterium Incorporation ◽  
Magnetic Resonance Studies ◽  
Exchange Processes ◽  
Nuclear Magnetic

Deuterium exchange occurs at five β positions in fenchone under homoenolization conditions (t-BuO−–t-BuOD, 185°), C-6(exo and endo), C-8, C-9, and C-10. Both13C and 2H n.m.r. methods were employed to monitor deuterium incorporation and the particular advantages of the latter are illustrated. The relative rates of the five exchange processes were determined directly by 2H n.m.r. in contrast to the earlier homoenolization studies for which the stereoselectivity of exchange was established indirectly. The intermediate homoenolate ion can lead to rearrangement and the rearrangement products have been characterized by 13C n.m.r. as the 3,3,6-trimethyl-norcamphors. Homoenolization of this mixture gave further evidence on the stereochemistry of homoenolate formation.

X-Ray crystallographic and 13C nuclear magnetic resonance studies of 3,4,5,6-tetrahydro-2H-1,3,4-oxadiazin-2-ones derived from ephedrine and pseudoephedrine

Tetrahedron ◽  
2001 ◽  
Vol 57 (49) ◽  
pp. 9789-9798 ◽  
Author(s):  
Shawn R Hitchcock ◽  
George P Nora ◽  
David M Casper ◽  
Michael D Squire ◽  
Christopher D Maroules ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Studies ◽  
X Ray ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

ChemInform Abstract: CARBON-13 NUCLEAR MAGNETIC RESONANCE RELAXATION IN HYDROGEN BONDED TERT-BUTYL ALCOHOL AND PHENOL

1975 ◽  
Vol 6 (29) ◽  
pp. no-no
Author(s):  
EDWIN E. TUCKER ◽  
THOMAS R. CLEM ◽  
JEFFREY I. SEEMAN ◽  
EDWIN D. BECKER
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Butyl Alcohol ◽  
Nuclear Magnetic Resonance Relaxation ◽  
Tert Butyl ◽  
Tert Butyl Alcohol ◽  
Resonance Relaxation ◽  
Nuclear Magnetic ◽  
Hydrogen Bonded

13C Nuclear Magnetic Resonance Studies of Organometallic Compounds. V. Di- and Trimethylplatinum(IV) Derivatives

1974 ◽  
Vol 52 (10) ◽  
pp. 1973-1982 ◽  
Author(s):  
Howard Charles Clark ◽  
Leo Ernest Manzer ◽  
John Edward Henry Ward
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Organometallic Compounds ◽  
Methyl Groups ◽  
Magnetic Resonance Studies ◽  
13C Nuclear Magnetic Resonance ◽  
Cis And Trans ◽  
Nuclear Magnetic

The 13C n.m.r. parameters for thirteen di- and trimethylplatinum(IV) derivatives have been obtained. It is shown that the 13C shieldings and 1JPtC and 2JPtCH values of methyl groups both cis and trans to varied ligands consistently follow trends similar to those found for related methylplatinum(II) derivatives.

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