13C magnetic resonance studies. 120. The Simmons–Smith reaction with some silyl enol ethers. Unusual ring expansions of some norcamphorsti

1985 ◽  
Vol 63 (11) ◽  
pp. 2969-2974 ◽  
Author(s):  
Arthur J. Ragauskas ◽  
J. B. Stothers
Keyword(s):  
Magnetic Resonance ◽  
Ring Expansion ◽  
Major Product ◽  
High Yield ◽  
Silyl Ether ◽  
Enol Ether ◽  
Enol Ethers ◽  
Magnetic Resonance Studies ◽  
Silyl Enol Ethers ◽  
Ring Expansions

Unexpected difficulties with Simmons–Smith cyclopropanation of the trimethylsilyl enol ether of exo-tricyclo[3.2.1.02,4]-octan-6-one led to a reexamination of this reaction with the parent norcamphor derivative which under "concentrated" conditions gave ring-expanded allylic ethers in low yield. With the tert-butyldimethylsilyl ethers, however, the allylic product is formed in high yield in the norcamphor and exo-trimethylenenorcamphor (tricyclo[5.2.1.02,6]decan-8-one) systems. The tert-butyldimethylsilyl enol ethers of bicyclo[3.2.1]octan-6-one and nopinone do not undergo ring expansion under similar conditions but the silyl ether of 3-methylenenopinol is a major product in the latter case.

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.

The chemistry of aryllead(IV) tricarboxylates. Reaction with silyl enol ethers

1982 ◽  
Vol 35 (11) ◽  
pp. 2237 ◽  
Author(s):  
HC Bell ◽  
JT Pinhey ◽  
S Sternhell
Keyword(s):  
Thermal Decomposition ◽  
Trifluoroacetic Acid ◽  
High Yield ◽  
Enol Ether ◽  
Enol Ethers ◽  
Silyl Enol Ethers ◽  
Lead Compounds ◽  
Considerable Detail ◽  
Aryl Ketone

The trimethylsilyl enol ether of acetophenone (1) and p-methoxyphenyllead triacetate (2) react to give (p-methoxyphenyl)phenacyllead(IV) diacetate (4) in high yield. This plumbation reaction has been studied for a number of ketone trimethylsilyl enol ethers and aryllead triacetates, and it would appear that it is probably limited to aryl ketone trimethylsilyl enol ethers. The trifluoroacetic acid catalysed break down of these α-plumbated ketones to substituted deoxybenzoins has been examined in considerable detail. The thermal decomposition of one of the lead compounds to a deoxybenzoin derivative has also been examined.

Carbon-carbon bond formation in reactions of PhIO.cntdot.HBF4-silyl enol ether adduct with alkenes or silyl enol ethers

1989 ◽  
Vol 54 (11) ◽  
pp. 2605-2608 ◽  
Author(s):  
V. V. Zhdankin ◽  
M. Mullikin ◽  
Rik Tykwinski ◽  
Bruce Berglund ◽  
Ronald Caple ◽  
...  
Keyword(s):  
Bond Formation ◽  
Enol Ether ◽  
Enol Ethers ◽  
Carbon Bond ◽  
Silyl Enol Ethers ◽  
Carbon Carbon Bond ◽  
Silyl Enol Ether

An Access to Highly Enantioenriched cis-3,5-Disubstituted γ-Lactones from α-Bromoacetate and Silyl Enol Ether

2021 ◽  
Author(s):  
Ha Rim Lee ◽  
Seo Yun Kim ◽  
Min Ji Park ◽  
Yong Sun Park
Keyword(s):  
Nucleophilic Substitution ◽  
Enol Ether ◽  
Enol Ethers ◽  
Silyl Enol Ethers ◽  
Synthetic Strategy ◽  
Silyl Enol Ether

A novel synthetic strategy for highly enantioenriched cis-3,5-disubstituted γ-lactones has been developed by the AgOTf-promoted nucleophilic substitution of α-bromoacetates with silyl enol ethers and subsequent reductive lactonization. The utility of...

ChemInform Abstract: Lewis Acid Mediated Ring Expansion Reaction of 2,3-Methanochromanones with Silyl Enol Ethers.

ChemInform ◽  
2010 ◽  
Vol 30 (50) ◽  
pp. no-no
Author(s):  
Yoshiaki Sugita ◽  
Kazuyoshi Kawai ◽  
Hiroki Hosoya ◽  
Ichiro Yokoe
Keyword(s):  
Lewis Acid ◽  
Ring Expansion ◽  
Enol Ethers ◽  
Silyl Enol Ethers ◽  
Ring Expansion Reaction

Studies of specifically fluorinated carbohydrates. Part IV. Addition of the elements of "CIF" to D-glucal triacetate

1969 ◽  
Vol 47 (3) ◽  
pp. 379-385 ◽  
Author(s):  
L. D. Hall ◽  
J. F. Manville
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Benzene Solution ◽  
Major Product ◽  
Magnetic Resonance Studies ◽  
Nuclear Magnetic

Reaction of chlorine with a suspension of D-glucal triacetate and silver monofluoride in an acetonitrile/benzene solution, affords a mixture of the four possible 2-chloro-2-deoxy-D-glycopyranosyl fluoride triacetates. The structures of these derivatives have been established by nuclear magnetic resonance studies and confirmed by independent syntheses. The major product is 2-chloro-2-deoxy-β-D-glucopyranosyl fluoride triacetate. These results are compared with those from the related "BrF" and "IF" additions.

Studies of specifically fluorinated carbohydrates. Part III. A new method for the addition of the elements of "BrF" and of "IF" to unsaturated carbohydrate derivatives

1969 ◽  
Vol 47 (3) ◽  
pp. 361-377 ◽  
Author(s):  
L. D. Hall ◽  
J. F. Manville
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Major Product ◽  
New Method ◽  
Magnetic Resonance Studies ◽  
Trans Addition

A smooth addition of the elements of "BrF", to D-glucal triacetate (1), occurs when bromine is reacted with 1 in the presence of silver monofluoride and a suitable solvent. This reaction affords a major product 2-bromo-2-deoxy-α-D-mannopyranosyl fluoride triacetate, together with smaller quantities of 2-bromo-2-deoxy-α-D-glucopyranosyl fluoride triacetate and the corresponding β-D-anomer. The structures of these products have been elucidated by fluorine and proton magnetic resonance studies, and confirmed by several independent syntheses. The same three products are obtained when "BrF" is generated insitu from N-bromosuccinimide and HF; however, under these conditions 2-deoxy-α-D-arabino-hexopyranosyl fluoride triacetate is also formed in ca. 7% yield. The Br2/AgF reagent has also been reacted with several 3,4-dihydro-2H-pyran derivatives and with other glycals. In all cases the major product(s) corresponds to the trans addition of "BrF". Similar results are obtained for the addition of the elements of "IF" to all of the above derivatives.

13C magnetic resonance studies. 144. An examination of β-enolization in the bicyclo[3.3.1]- and [3.2.2]nonan-2-one system

1993 ◽  
Vol 71 (8) ◽  
pp. 1099-1105 ◽  
Author(s):  
David J. Muir ◽  
J.B. Stothers
Keyword(s):  
Electron Transfer ◽  
Magnetic Resonance ◽  
Major Product ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Magnetic Resonance Studies ◽  
Unsaturated Ketones ◽  
A Minor ◽  
Cis And Trans ◽  
Magnetic Resonance Spectra

While 3,3-dimethylbicyclo[3.3.1]nonan-2-one (5) is stable under strongly basic conditions (t-BuO−/t-BuOH/185 °C), its isomer, 3,3-dimethylbicyclo[3.2.2]nonan-2-one (6), is slowly transformed to 5. Similarly, 3,3-dimethylbicyclo-[3.2.2]non-6-en-2-one (8b) rearranges to a [3.3.1] isomer but the latter is not stable. Experiments with 3,3-dimethylbicyclo[3.3.1]non-6-en-2-one (7) revealed that it is converted to five compounds, none of which is 8b. The major product, 8,8-dimethylbicyclo[4.3.0]non-1(6),-en-7-one (11) arises from β-enolate rearrangement. Enone 11 undergoes slow reduction to cis- and trans-8,8-dimethylbicyclo[4.3.0]nonan-7-one, presumably by single electron transfer. Experiments with 11 alone showed that β-enolate rearrangement of 7 → 11 is unidirectional. Haller–Bauer cleavage to acidic products occurs as a minor process in the reactions of the unsaturated ketones. The structures of the products were established primarily from their 1H and 13C magnetic resonance spectra.

ChemInform Abstract: Carbon-Carbon Bond Formation in Reactions of PhIO·HBF4/Silyl Enol Ether Adduct with Alkenes or Silyl Enol Ethers.

ChemInform ◽  
1989 ◽  
Vol 20 (47) ◽  
Author(s):  
V. V. ZHDANKIN ◽  
M. MULLIKIN ◽  
R. TYKWINSKI ◽  
B. BERGLUND ◽  
R. CAPLE ◽  
...  
Keyword(s):  
Bond Formation ◽  
Enol Ether ◽  
Enol Ethers ◽  
Carbon Bond ◽  
Silyl Enol Ethers ◽  
Carbon Carbon Bond ◽  
Silyl Enol Ether
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