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.

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.

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

A new preparative ring expansion for bicyclic ketones. Homoketonization of cyclopropoxide analogs

1980 ◽  
Vol 58 (23) ◽  
pp. 2730-2732 ◽  
Author(s):  
Yumiko Hoyano ◽  
Vijay Patel ◽  
J. B. Stothers
Keyword(s):  
Ring Expansion ◽  
Synthetic Method ◽  
Ring Systems ◽  
Bicyclic Ketones

Homoketonization of some readily prepared cyclopropoxides affords a new synthetic method for ring expansion of the [2.2.1] and [2.2.2] ring systems.

HClO4 catalysed aldol-type reaction of fluorinated silyl enol ethers with acetals or ketals toward fluoroalkyl ethers

2019 ◽  
Vol 17 (43) ◽  
pp. 9430-9434 ◽  
Author(s):  
You-Ping Tian ◽  
Yi Gong ◽  
Xiao-Si Hu ◽  
Jin-Sheng Yu ◽  
Ying Zhou ◽  
...  
Keyword(s):  
Enol Ethers ◽  
Silyl Ethers ◽  
Silyl Enol Ethers ◽  
Metal Free ◽  
Type Reaction ◽  
Highly Efficient ◽  
Enol Silyl Ethers

A highly efficient metal-free catalytic aldol-type reaction of fluorinated enol silyl ethers and acetals/ketals toward functionalized fluoroalkyl ethers is developed by using less than 1.0 mol% HClO4 (70 wt%, aq.).

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.

Organocatalytic enantioselective Mukaiyama–Mannich reaction of fluorinated enol silyl ethers and cyclic N-sulfonyl ketimines

2016 ◽  
Vol 3 (3) ◽  
pp. 298-303 ◽  
Author(s):  
Jin-Sheng Yu ◽  
Jian Zhou
Keyword(s):  
Amino Acid ◽  
Mannich Reaction ◽  
Enantioselective Synthesis ◽  
Amino Acid Derivatives ◽  
Enol Ethers ◽  
Silyl Ethers ◽  
Silyl Enol Ethers ◽  
Catalytic Asymmetric ◽  
Enol Silyl Ethers

The first catalytic asymmetric Mukaiyama–Mannich reaction of fluorinated silyl enol ethers and ketimines is developed, allowing highly enantioselective synthesis of benzosultam based β-fluorinated Cα-tetrasubstituted α-amino acid derivatives.

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.

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