scholarly journals Studies of Strained Ring Systems: Cyclopropa[1]Phenanthrenes

2021 ◽  
Author(s):  
◽  
Barry Roy Dent
Keyword(s):  
Carboxylic Acid ◽  
Model Compound ◽  
Structural Type ◽  
Ring System ◽  
Convincing Evidence ◽  
Conclusive Evidence ◽  
Oxidative Decarboxylation ◽  
Fluoride Ion ◽  
Allyl Cation ◽  
Dichloro Derivative

<p>The aim of the present study has been the synthesis of 1H-cyclo-Propa[1]phenanthrene (16a) and its derivatives, the sole remaining unknown structural type of the cycloproparenes. Established procedures for cycloproparene synthesis are not readily adaptable to this ring system, and routes based upon new bridge-head-substituted 1a,9b-dihydrocyclopropa[1]phenanthrenes are examined. 1, 1-Dichloro-1a-phenylseleno-1a, 9b-dihydrocyclopropa [1] phenanthrene (73) is prepared by the addition of dichlorocarbene to the corresponding phenanthrenyl selenide (72). syn-Selenoxide elimination of PhSeOH from the derived selenoxide (74) gives 1,1-dichloro-1H-cyclopropa[1]phenanthrene (76) which is intercepted by methanolysis. Labelling studies provide convincing evidence for the intermediacy of the 1H-cycloproparene. The viability of an oxidative decarboxylation route to 1,1-dialkyl-1H-cyclopropa[1]phenanthrenes is investigated for the model compound 7,7-dimethylbicyclo[4.1.0]hept-3-ene-1-carboxylic acid (122). A product of formal cyclopropyl-allyl cation rearrangement, is isolated. 1a-Methylseleno-1a,9b-dihydrocyclopropa[1]phenanthrenes (174) is prepared by the unprecedented addition of methylselenide anion to 1aH-cyclopropa[1]phenanthrene (63) (generated by a new route involving the fluoride ion-promoted elimination of the elements of chlorotrimethylsilane from the isomeric 1-chloro-1a-trimethylsilyl-1a, 9b-dihydrocyclopropa[1]phenanthrenes (170) and (171)). Treatment of the drived dimethylselenonium tetra-fluoroborate (179) with base in the presence of furan gives the endo- and exo-furan cycloadducts (180) and (181) of 1H-cyclopropa[1]phenanthrene (16a). The results presented herein provide the first conclusive evidence for the existence of the 1H-cyclopropa[1]phenanthrene ring system, both as the parent hydrocarbon (16a) and the 1,1-dichloro-derivative(76).</p>

scholarly journals Studies of Strained Ring Systems: Cyclopropa[1]Phenanthrenes

2021 ◽  
Author(s):  
◽  
Barry Roy Dent
Keyword(s):  
Carboxylic Acid ◽  
Model Compound ◽  
Structural Type ◽  
Ring System ◽  
Convincing Evidence ◽  
Conclusive Evidence ◽  
Oxidative Decarboxylation ◽  
Fluoride Ion ◽  
Allyl Cation ◽  
Dichloro Derivative

<p>The aim of the present study has been the synthesis of 1H-cyclo-Propa[1]phenanthrene (16a) and its derivatives, the sole remaining unknown structural type of the cycloproparenes. Established procedures for cycloproparene synthesis are not readily adaptable to this ring system, and routes based upon new bridge-head-substituted 1a,9b-dihydrocyclopropa[1]phenanthrenes are examined. 1, 1-Dichloro-1a-phenylseleno-1a, 9b-dihydrocyclopropa [1] phenanthrene (73) is prepared by the addition of dichlorocarbene to the corresponding phenanthrenyl selenide (72). syn-Selenoxide elimination of PhSeOH from the derived selenoxide (74) gives 1,1-dichloro-1H-cyclopropa[1]phenanthrene (76) which is intercepted by methanolysis. Labelling studies provide convincing evidence for the intermediacy of the 1H-cycloproparene. The viability of an oxidative decarboxylation route to 1,1-dialkyl-1H-cyclopropa[1]phenanthrenes is investigated for the model compound 7,7-dimethylbicyclo[4.1.0]hept-3-ene-1-carboxylic acid (122). A product of formal cyclopropyl-allyl cation rearrangement, is isolated. 1a-Methylseleno-1a,9b-dihydrocyclopropa[1]phenanthrenes (174) is prepared by the unprecedented addition of methylselenide anion to 1aH-cyclopropa[1]phenanthrene (63) (generated by a new route involving the fluoride ion-promoted elimination of the elements of chlorotrimethylsilane from the isomeric 1-chloro-1a-trimethylsilyl-1a, 9b-dihydrocyclopropa[1]phenanthrenes (170) and (171)). Treatment of the drived dimethylselenonium tetra-fluoroborate (179) with base in the presence of furan gives the endo- and exo-furan cycloadducts (180) and (181) of 1H-cyclopropa[1]phenanthrene (16a). The results presented herein provide the first conclusive evidence for the existence of the 1H-cyclopropa[1]phenanthrene ring system, both as the parent hydrocarbon (16a) and the 1,1-dichloro-derivative(76).</p>

scholarly journals Studies of Strained Ring Systems: Cyclopropa[1]Phenanthrenes

2021 ◽  
Author(s):  
◽  
Barry Roy Dent
Keyword(s):  
Carboxylic Acid ◽  
Model Compound ◽  
Structural Type ◽  
Ring System ◽  
Convincing Evidence ◽  
Conclusive Evidence ◽  
Oxidative Decarboxylation ◽  
Fluoride Ion ◽  
Allyl Cation ◽  
Dichloro Derivative

<p>The aim of the present study has been the synthesis of 1H-cyclo-Propa[1]phenanthrene (16a) and its derivatives, the sole remaining unknown structural type of the cycloproparenes. Established procedures for cycloproparene synthesis are not readily adaptable to this ring system, and routes based upon new bridge-head-substituted 1a,9b-dihydrocyclopropa[1]phenanthrenes are examined. 1, 1-Dichloro-1a-phenylseleno-1a, 9b-dihydrocyclopropa [1] phenanthrene (73) is prepared by the addition of dichlorocarbene to the corresponding phenanthrenyl selenide (72). syn-Selenoxide elimination of PhSeOH from the derived selenoxide (74) gives 1,1-dichloro-1H-cyclopropa[1]phenanthrene (76) which is intercepted by methanolysis. Labelling studies provide convincing evidence for the intermediacy of the 1H-cycloproparene. The viability of an oxidative decarboxylation route to 1,1-dialkyl-1H-cyclopropa[1]phenanthrenes is investigated for the model compound 7,7-dimethylbicyclo[4.1.0]hept-3-ene-1-carboxylic acid (122). A product of formal cyclopropyl-allyl cation rearrangement, is isolated. 1a-Methylseleno-1a,9b-dihydrocyclopropa[1]phenanthrenes (174) is prepared by the unprecedented addition of methylselenide anion to 1aH-cyclopropa[1]phenanthrene (63) (generated by a new route involving the fluoride ion-promoted elimination of the elements of chlorotrimethylsilane from the isomeric 1-chloro-1a-trimethylsilyl-1a, 9b-dihydrocyclopropa[1]phenanthrenes (170) and (171)). Treatment of the drived dimethylselenonium tetra-fluoroborate (179) with base in the presence of furan gives the endo- and exo-furan cycloadducts (180) and (181) of 1H-cyclopropa[1]phenanthrene (16a). The results presented herein provide the first conclusive evidence for the existence of the 1H-cyclopropa[1]phenanthrene ring system, both as the parent hydrocarbon (16a) and the 1,1-dichloro-derivative(76).</p>

scholarly journals Studies of Strained Ring Systems: Cyclopropa[1]Phenanthrenes

2021 ◽  
Author(s):  
◽  
Barry Roy Dent
Keyword(s):  
Carboxylic Acid ◽  
Model Compound ◽  
Structural Type ◽  
Ring System ◽  
Convincing Evidence ◽  
Conclusive Evidence ◽  
Oxidative Decarboxylation ◽  
Fluoride Ion ◽  
Allyl Cation ◽  
Dichloro Derivative

<p>The aim of the present study has been the synthesis of 1H-cyclo-Propa[1]phenanthrene (16a) and its derivatives, the sole remaining unknown structural type of the cycloproparenes. Established procedures for cycloproparene synthesis are not readily adaptable to this ring system, and routes based upon new bridge-head-substituted 1a,9b-dihydrocyclopropa[1]phenanthrenes are examined. 1, 1-Dichloro-1a-phenylseleno-1a, 9b-dihydrocyclopropa [1] phenanthrene (73) is prepared by the addition of dichlorocarbene to the corresponding phenanthrenyl selenide (72). syn-Selenoxide elimination of PhSeOH from the derived selenoxide (74) gives 1,1-dichloro-1H-cyclopropa[1]phenanthrene (76) which is intercepted by methanolysis. Labelling studies provide convincing evidence for the intermediacy of the 1H-cycloproparene. The viability of an oxidative decarboxylation route to 1,1-dialkyl-1H-cyclopropa[1]phenanthrenes is investigated for the model compound 7,7-dimethylbicyclo[4.1.0]hept-3-ene-1-carboxylic acid (122). A product of formal cyclopropyl-allyl cation rearrangement, is isolated. 1a-Methylseleno-1a,9b-dihydrocyclopropa[1]phenanthrenes (174) is prepared by the unprecedented addition of methylselenide anion to 1aH-cyclopropa[1]phenanthrene (63) (generated by a new route involving the fluoride ion-promoted elimination of the elements of chlorotrimethylsilane from the isomeric 1-chloro-1a-trimethylsilyl-1a, 9b-dihydrocyclopropa[1]phenanthrenes (170) and (171)). Treatment of the drived dimethylselenonium tetra-fluoroborate (179) with base in the presence of furan gives the endo- and exo-furan cycloadducts (180) and (181) of 1H-cyclopropa[1]phenanthrene (16a). The results presented herein provide the first conclusive evidence for the existence of the 1H-cyclopropa[1]phenanthrene ring system, both as the parent hydrocarbon (16a) and the 1,1-dichloro-derivative(76).</p>

scholarly journals 6-(Hex-5-enyloxy)naphthalene-2-carboxylic acid

2014 ◽  
Vol 70 (6) ◽  
pp. o696-o697
Author(s):  
Md. Lutfor Rahman ◽  
H. T. Srinivasa ◽  
Mashitah Mohd. Yusoff ◽  
Huey Chong Kwong ◽  
Ching Kheng Quah
Keyword(s):  
Crystal Structure ◽  
Carboxylic Acid ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Ring System ◽  
Dihedral Angles ◽  
Carbonyl Groups ◽  
Asymmetric Unit ◽  
Compound C ◽  
Independent Molecules

The asymmetric unit of the title compound, C17H18O3, comprises three independent molecules with similar geometries. In each molecule, the carbonyl group is twisted away from the napthalene ring system, making dihedral angles of 1.0 (2), 1.05 (19)° and 1.5 (2)°. The butene group in all three molecules are disordered over two sets of sites, with a refined occupancy ratio of 0.664 (6):0.336 (6). In the crystal, molecules are oriented with respect to their carbonyl groups, forming head-to-head dimersviaO—H...O hydrogen bonds. Adjacent dimers are further interconnected by C—H...O hydrogen bonds into chains along thea-axis direction. The crystal structure is further stabilized by weak C—H...π interactions.

The camphenehydro (methylcamphenilyl) and isobornyl (bornyl) cations. III. Oxidative decarboxylation of carboxylic acids with lead tetraacetate

1974 ◽  
Vol 27 (3) ◽  
pp. 603 ◽  
Author(s):  
GE Gream ◽  
CF Pincombe ◽  
D Wege
Keyword(s):  
Carboxylic Acid ◽  
Marked Change ◽  
Lead Tetraacetate ◽  
Dimethyl Sulphoxide ◽  
Oxidative Decarboxylation ◽  
Propanoic Acid ◽  
Acid Yield ◽  
Cupric Acetate ◽  
Initial Generation ◽  
Almost All

The oxidative decarboxylation of exo- and endo-bornane-2-carboxylic acid, exo- and endo-2,3,3- trimethylnorbornane-2-carboxylic acid and a-campholenylcarboxylic acid [3-(2',2',3'-trimethyl- cyclopent-3'-eny1)propanoic acid] with lead tetraacetate in benzene and dimethyl sulphoxide (each containing pyridine) in the presence, and absence, of cupric acetate has been investigated. The mode of formation of almost all the products can be satisfactorily rationalized in terms of the initial generation of radicals. In the case of exo- and endo-bornane-2-carboxylic acid, the derived bornyl radical forms organolead and organocopper derivatives that decompose in three ways: (1) by heterolysis by the direct route to give the equilibrating isobornyl and camphenehydro cations, (2) by a cyclic cis-elimination to give bornylene and (3) by an SNi process to give isobornyl and bornyl acetates. exo- and endo-2,3,3-Trimethylnorbornane-2-carboxylic acid yield the 2,3,3-trimethyl- norborn-2-yl radical which is converted into the equilibrating camphenehydro and isobornyl cations either by one-electron oxidation by lead species or via organolead or organocopper derivatives which undergo heterolysis. Processes involving cyclic cis-elimination and SNi substitution may also operate in the organometallic derivatives derived from the tertiary radical. a-Campholenylcarboxylic acid yields the a-campholenyl radical which, in the absence of cupric acetate, undergoes in the main cyclization to give the 2,3,3-trimethylnorbornyl radical. The resulting mixture of products is similar to that obtained from exo- and endo-2,3,3-trimethylnorbornane-2- carboxylic acid. In the presence of cupric acetate, the a-campholenyl radical is trapped at least to the extent of 50% in benzene and 80% in dimethyl sulphoxide to give the corresponding organo- copper derivative which undergoes a cyclic elimination to give 2,3,3-trimethyl-4-vinylcyclopentene and may undergo heterolysis by the x-route to give the camphenehydro and isobornyl cations. A marked change in the composition of the products on changing the solvent from benzene to dimethyl sulphoxide is observed only in the case of a-campholenylcarboxylic acid in the presence of cupric acetate.

scholarly journals Crystal structure of (3S*,4R*)-4-fluoro-3-(4-methoxyphenyl)-1-oxo-2-phenyl-1,2,3,4-tetrahydroisoquinoline-4-carboxylic acid

2017 ◽  
Vol 73 (6) ◽  
pp. 867-870
Author(s):  
Anna Lehmann ◽  
Lisa Lechner ◽  
Krzysztof Radacki ◽  
Holger Braunschweig ◽  
Ulrike Holzgrabe
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Carboxylic Acid ◽  
Phenyl Ring ◽  
Ring System ◽  
Piperidine Ring ◽  
Boat Conformation ◽  
Bond Forming ◽  
Compound C ◽  
The Mean

The title compound, C23H18FNO4, crystallized as a racemate. It exhibits acisconformation with respect to the F atom and the methine H atom. The piperidine ring has a screw-boat conformation. The methoxyphenyl ring and the phenyl ring are inclined to the mean plane of the isoquinoline ring system by 89.85 (4) and 46.62 (5)°, respectively, and by 78.15 (5)° to one another. In the crystal, molecules are linked by an O—H...O hydrogen bond forming chains propagating along thea-axis direction. The chains are linked by C—H...F hydrogen bonds, forming layers lying parallel to theabplane.

scholarly journals Six-Step Gram Scale Synthesis of the HIV Integrase Inhibitor Dolutegravir Sodium

2021 ◽  
Author(s):  
Jule-Phillip Dietz ◽  
Tobias Lucas ◽  
Jonathan Groß ◽  
Sebastian Seitel ◽  
Jan Brauer ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Integrase Inhibitor ◽  
Active Pharmaceutical Ingredient ◽  
Ring System ◽  
Hiv Integrase ◽  
Salt Formation ◽  
One Pot ◽  
Amide Formation ◽  
Practical Synthesis

A short and practical synthesis for preparing the active pharmaceutical ingredient dolutegravir sodium was investigated. The convergent strategy developed herein starts from 3-(R)-amino-1- butanol and builds up the BC ring system in 76% isolated yield over four steps. Ring A was constructed by a one-pot 1,4-addition to diethyl-(2E/Z)-2-(ethoxymethylidene)-3-oxobutandioate and subsequent MgBr2·OEt2-mediated regioselective cyclization. Amide formation with 2,4- difluorobenzylamine was either performed from the carboxylic acid or through aminolysis of the corresponding ester precursor. Final salt formation afforded dolutegravir sodium in 48–51% isolated yield (HPLC-purity: 99.7–99.9%) over six linear steps.<br>

Weak dynamical effects in the Uranian ring system

1984 ◽  
Vol 75 ◽  
pp. 457-458
Author(s):  
Adam P. Freedman ◽  
Scott Tremaine ◽  
James L. Elliot
Keyword(s):  
Close Association ◽  
Ring System ◽  
Convincing Evidence ◽  
Gravitational Forces ◽  
Ring Model ◽  
Maximum Change ◽  
Uranian Ring ◽  
The Masses ◽  
Three Body ◽  
Residual Errors

ABSTRACTA number of weak gravitational forces were examined for their kinematic effects on the Uranian ring system, in an attempt to account for residual errors of ~2 km in the ring positions and a few times 10-3deg/day in the apse precession rates. The principal conclusions are as follows: (1) perturbations by the five known satellites are too small to have observable effects with the best current estimates of the satellite masses. (2) Limits can be set on the masses of inter-ring “shepherd” satellites from their influence on precession rates and their radial perturbations on the rings. For example, the maximum mass of a shepherd satellite between rings 4 and 5 is ~ 1019gm. (3) Using the best available ring parameters, there is no convincing evidence that the rings are associated with resonances with known satellites. The only close association is of rings 5, α and γ with three-body resonances due to Miranda and Ariel. It is more likely that the putative shepherd satellites may occupy resonances. (4) The known satellites can cause anomalous residuals by changing the position of Uranus relative to the system barycenter during the occultation. The maximum change, so far, during the 1977 March 10 event, was 1.6 km. This effect will be investigated with the MIT Uranus ring model.

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