Le radical méthylènecyclopropyle: étude théorique. Chloration par t-BuOCl et réduction par (nBu)3SnH de dérivés cyclopropéniques

1985 ◽  
Vol 63 (9) ◽  
pp. 2511-2521 ◽  
Author(s):  
R. Arnaud ◽  
S. Choubani ◽  
R. Subra ◽  
M. Vidal ◽  
M. Vincens ◽  
...  
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Ring Opening ◽  
Functional Group ◽  
Theoretical Study ◽  
Reduction Process ◽  
Trans Position ◽  
Tertiary Alcohols ◽  
Abstraction Reaction ◽  
Allylic Radical

The allylic chlorination of ethyl 2,3-dialkyl 2-cyclopropenecarboxylate or primary and tertiary alcohols is highly regio- and stereoselective. The halogenated methylenecyclopropane derivative only is observed. In that compound, the halogen substituent and the functional group are in a trans position with respect to the ring. The halogenated allylic compounds of methylenecyclopropane and of cyclopropene undergo reduction by (nBu)3SnH with the same stereochemistry. Products arising from ring opening are also observed. The exocyclic migration of the double bond can be related to the formation of a transient allylic radical. A theoretical study performed within the MNDO (UHF and RHF) framework leads to a planar allylic radical, whatever the substituent. The radical abstraction reaction which takes place during the reduction process is easier for a cyclic carbon atom than for an exocyclic one. In the former case, the faster reaction is obtained for a chlorinated carbon atom.

scholarly journals Visible light mediated photocatalytic [2 + 2] cycloaddition/ring-opening rearomatization cascade of electron-deficient azaarenes and vinylarenes

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Noelia Salaverri ◽  
Rubén Mas-Ballesté ◽  
Leyre Marzo ◽  
José Alemán
Keyword(s):  
Natural Products ◽  
Double Bond ◽  
Visible Light ◽  
Bioactive Compounds ◽  
Late Stage ◽  
Ring Opening ◽  
Functional Group ◽  
Theoretical Calculations ◽  
Double Bonds ◽  
Heterocyclic Derivatives

Abstract The broad presence of azaarene moieties in natural products has promoted the development of new functionalization reactions, giving access to larger libraries of bioactive compounds. The light promoted [2 + 2] photocycloaddition reaction to generate cyclobutanes has been extensively studied in photochemistry. In particular, De Mayo reported the [2 + 2] cycloaddition followed by retroaldol condensation between enols of 1,3-dicarbonyls and double bonds to synthesize 1,5-dicarbonyls. Herein, we describe the [2 + 2] photocycloaddition followed by a ring-opening rearomatization reaction between electron-deficient 2-methylene-azaarenes and double bonds, taking advantage of the ability of these heterocyclic derivatives to form the corresponding pseudo-enamine intermediate. The procedure shows a high functional group tolerance either on the double bond or the heteroarene side and allows the presence of different electron-withdrawing groups. In addition, the wide applicability of this reaction has been demonstrated through the late-stage derivatization of several natural products. Photochemical studies, together with theoretical calculations, support a mechanism involving the photosensitization of the pseudo-enamine intermediate.

THEORETICAL STUDY OF THE REGIOSELECTIVITY OF THE ADDITION OF THE TRIPLET OXYGEN ATOM TO UNSYMMETRICAL SUBSTITUTED ALKENES

2012 ◽  
Vol 11 (03) ◽  
pp. 527-535 ◽  
Author(s):  
BOULANOUAR MESSAOUDI ◽  
SIDI MOHAMED MEKELLECHE ◽  
NELAINE MORA-DIEZ
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Oxygen Atom ◽  
Theoretical Study ◽  
Transition States ◽  
Reaction Pathways ◽  
Fukui Indices ◽  
Radical Attack ◽  
Spin Densities ◽  
Good Agreement

A theoretical study of the reactivity and regioselectivity of the addition of the triplet oxygen atom O(3P) to a series of unsymmetrical substituted alkenes has been performed at the PMP2/6-311++G (d,p) level of theory. Two reaction pathways, namely, the addition to the substituted carbon atom (α-site) and addition to the non-substituted carbon atom (β-site), have been studied. Our calculations show that the β-addition products are kinetically more favored; whereas the α-addition products are found to be thermodynamically more stable. The regioselectivity (α vs. β) of the addition of the O(3P) to the carbon–carbon double bond is predicted by means of the relative energies of the localized transition states and also by the calculation of spin densities of the 3ππ* states of reactants and Fukui indices corresponding to the radical attack to alkenes. Our calculations are in good agreement with experimental outcomes.

Functional group dependence of the acid catalyzed ring opening of biomass derived furan rings: an experimental and theoretical study

2013 ◽  
Vol 3 (1) ◽  
pp. 106-115 ◽  
Author(s):  
Christopher R. Waidmann ◽  
Aaron W. Pierpont ◽  
Enrique R. Batista ◽  
John C. Gordon ◽  
Richard L. Martin ◽  
...  
Keyword(s):  
Ring Opening ◽  
Functional Group ◽  
Theoretical Study ◽  
Acid Catalyzed

Reactions of 4-Pyrones with Azomethine Ylides as a Chemo­selective Method for the Construction of Multisubstituted Pyrano[2,3-c]pyrrolidines

Synthesis ◽  
2021 ◽  
Author(s):  
Dmitrii L. Obydennov ◽  
Vyacheslav D. Steben’kov ◽  
Konstantin L. Obydennov ◽  
Sergey A. Usachev ◽  
Vladimir S. Moshkin ◽  
...  
Keyword(s):  
Double Bond ◽  
Ring Opening ◽  
Azomethine Ylides ◽  
Azomethine Ylide ◽  
Dipolar Cycloaddition ◽  
Computational Studies ◽  
Carbon Double Bond ◽  
Reactivity Indexes ◽  
Reaction Proceeds

Abstract4-Pyrones bearing electron-donating and electron-withdrawing groups react with nonstabilized azomethine ylides to form pyrano[2,3-c]pyrrolidines in moderate to good yields. The reaction proceeds chemoselectively as a 1,3-dipolar cycloaddition of the azomethine ylide at the carbon–carbon double bond of the pyrone activated by the electron-withdrawing substituent. The reactivity of 4-pyrones toward azomethine ylides was rationalized by computational studies with the use of reactivity indexes. The pyrano[2,3-c]pyrrolidine moiety could be modified, for example by a ring-opening transformation under the action of hydrazine to provide pyrazolyl-substituted pyrrolidines.

Theoretical study of photoinduced ring-opening in furan

2010 ◽  
Vol 133 (16) ◽  
pp. 164309 ◽  
Author(s):  
E. V. Gromov ◽  
A. B. Trofimov ◽  
F. Gatti ◽  
H. Köppel
Keyword(s):  
Ring Opening ◽  
Theoretical Study

Reactions of N+ ions with ethylene: a theoretical study on the addition mechanism into the olefin double bond

2004 ◽  
Vol 297 (1-3) ◽  
pp. 121-131 ◽  
Author(s):  
Marco Di Stefano ◽  
Marzio Rosi ◽  
Antonio Sgamellotti
Keyword(s):  
Double Bond ◽  
Theoretical Study

Theoretical study of stereodynamics for the D′ + DS(v= 0,j= 0) → D′D + S abstraction reaction

2013 ◽  
Vol 22 (5) ◽  
pp. 053402 ◽  
Author(s):  
Ya-Hui Guo ◽  
Feng-Yun Zhang ◽  
Hong-Zhang Ma
Keyword(s):  
Theoretical Study ◽  
Abstraction Reaction

scholarly journals Theoretical Study of the Double-Bond Isomerization of 1-Hexene to cis-2-Hexene over ZSM-5 Zeolite

2011 ◽  
Vol 27 (05) ◽  
pp. 1081-1088
Author(s):  
LI Yan-Feng ◽  
◽  
ZHU Ji-Qin ◽  
LIU Hui ◽  
HE Peng ◽  
...  
Keyword(s):  
Double Bond ◽  
Theoretical Study ◽  
Double Bond Isomerization

scholarly journals THEORETICAL STUDY OF THE REACTION MECHANISM 1,2-ETHANEDIIOL WITH 1,3-DICHLOROPROPENE

2020 ◽  
Vol 2018 (1) ◽  
pp. 68-77
Author(s):  
Elena Chirkina ◽  
Leonid Krivdin ◽  
Nikolay Korchevin
Keyword(s):  
Carbon Atom ◽  
Chlorine Atom ◽  
Sulfur Atom ◽  
Density Functional ◽  
Theoretical Study ◽  
Thiol Group ◽  
Nucleophilic Attack ◽  
Substitution Product ◽  
Reaction Proceeds ◽  
Theoretical Mechanism

The theoretical mechanism of the interaction of 1,3-dichloropropene with 1,2-ethanedithiol in the system "hydrazine hydrate-KOH" has been proposed by the method of B3LYP / 6-311 ++ G (d, p) in the framework of the theory of the electron-density functional according to which the reaction proceeds successively in several stages, including the nucleophilic substitution of the chlorine atom present in the sp3-hybridized carbon atom with a sulfur atom to form a mono-substitution product that undergoes a prototropic allylic rearrangement that migrates the double bond to the sulfur atom, followed by closure in the dithiolane cycle due to the nucleophilic attack of the sulfide anion of the second thiol group of the reagent per carbon atom located in the γ-position with respect to the second chlorine atom.

scholarly journals Ester Dance Reaction on the Aromatic Ring

2019 ◽  
Author(s):  
Kaoru Matsushita ◽  
Ryosuke Takise ◽  
Kei Muto ◽  
Junichiro Yamaguchi
Keyword(s):  
Carbon Atom ◽  
Aromatic Ring ◽  
Functional Group ◽  
State Of The Art ◽  
Palladium Catalysis ◽  
Ester Group ◽  
Halogen Atoms ◽  
Ester Moiety ◽  
Rearrangement Reactions ◽  
Halogen Dance Reaction

Aromatic rearrangement reactions are useful tools in the organic chemist’s toolbox when generating uncommon substitution patterns. However, it is difficult to precisely translocate a functional group in (hetero)arene systems, with the exception of halogen atoms in a halogen dance reaction. Herein, we describe an unprecedented “ester dance” reaction: a predictable translocation of an ester group from one carbon atom to another on an aromatic ring. Specifically, a phenyl carboxylate substituent can be shifted from one carbon to an adjacent carbon on a (hetero)aromatic ring under palladium catalysis to often give a thermodynamically favored, regioisomeric product with modest to good conversions. The obtained ester moiety can be further converted to various aromatic derivatives through the use of classic as well as state-of-the-art transformations including an amidation, acylations and decarbonylative couplings.

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