scholarly journals Intramolecular Friedel–Crafts alkylation with a silylium-ion-activated cyclopropyl group: formation of tricyclic ring systems from benzyl-substituted vinylcyclopropanes and hydrosilanes

2021 ◽  
Author(s):  
Tao He ◽  
Guoqiang Wang ◽  
Peng-Wei Long ◽  
Sebastian Kemper ◽  
Elisabeth Irran ◽  
...  
Keyword(s):  
Cyclopropane Ring ◽  
Group Formation ◽  
Aryl Group ◽  
Ring Systems ◽  
Cyclopropyl Group

Downstream to alkene hydrosilylation, the opening of the cyclopropane ring in benzyl-substituted VCPs is interlinked with an SEAr of the aryl group.

10.24.4 Product Subclass 4: Pyrazino[1,2-a]indoles and Related Benzo-Fused Ring Systems

2021 ◽  
Author(s):  
P. A. Harris
Keyword(s):  
Indole Derivatives ◽  
Aryl Group ◽  
Ring Systems ◽  
Keto Ester ◽  
Fused Ring

AbstractThe synthesis of pyrazino[1,2-a]indoles and related indolo[1,2-a]quinoxalines and pyrido[2′,1′:3,4]pyrazino[1,2-a]indol-5-ium salts are reviewed in this chapter. The most common routes to pyrazino[1,2-a]indoles involve cyclization of indole derivatives containing a formyl, keto, ester, or nitrile function at the 2-position. Indolo[1,2-a]quinoxalines are most readily accessed via cyclization of 1-(aryl)-1H-indoles, where the aryl group is substituted at the 2-position by either amino, iodo, or nitro functionality.

Facile Synthesis of Polysubstituted 2-Pyrones via TfOH-Mediated Ring Expansion of 2-Acylcyclopropane-1-Carboxylates

Synthesis ◽  
2021 ◽  
Author(s):  
Jiru Shao ◽  
Caiyun An ◽  
Sunewang Rixin Wang
Keyword(s):  
Cyclopropane Ring ◽  
Bond Cleavage ◽  
Ring Expansion ◽  
Facile Synthesis ◽  
Aryl Group ◽  
Pyrone Ring ◽  
Donor Acceptor ◽  
Facile Route

A facile route to polysubstituted 2-pyrones from readily available 2-acylcyclopropane-1-aryl-1-carboxylates mediated by TfOH is reported. The strongly donating 1-aryl group is important for directing the C-C bond cleavage of the donor-acceptor cyclopropane ring, which then leads to the formation of the 2-pyrone ring through lactonization.

(E)-3-(2-Chloro-3,3,3-trifluoroprop-1-enyl)-N-(9,10-dioxo-9,10-dihydroanthracen-1-yl)-2,2-dimethylcyclopropanecarboxamide

2007 ◽  
Vol 63 (11) ◽  
pp. o4201-o4201
Author(s):  
Fan-Yong Yan ◽  
Dong-Qing Liu
Keyword(s):  
Hydrogen Bond ◽  
Dihedral Angle ◽  
Intramolecular Hydrogen Bond ◽  
Title Compound ◽  
Crystal Packing ◽  
Cyclopropane Ring ◽  
Ring Systems ◽  
Compound C ◽  
Intramolecular Hydrogen

In the title compound, C23H17ClF3NO3, the dihedral angle between the dihydroanthracene and cyclopropane ring systems is 58.5 (4)°. The amino H atom forms an intramolecular hydrogen bond to a carbonyl O atom of the dioxodihydroanthracene moiety. The crystal packing is further stabilized by an intermolecular C—H...F contact.

Ring constructions by the use of fluorine substituent as activator and controller

2000 ◽  
Vol 72 (9) ◽  
pp. 1685-1689 ◽  
Author(s):  
Junji Ichikawa
Keyword(s):  
Reaction Pathways ◽  
Electronic Effects ◽  
Aryl Group ◽  
Ring Systems ◽  
Leaving Group ◽  
Fused Ring ◽  
Intramolecular Substitution ◽  
Leaving Group Ability ◽  
Nucleophilic Center

By using the properties of fluorine such as electronic effects and leaving-group ability, two types of ring-forming reactions have been achieved starting from fluoroolefins: (i) fluorinated vinyl ketones with a vinyl and/or an aryl group, which undergo fluorine-directed and/or -activated Nazarov, Friedel-Crafts, and tandem cyclizations in their combination to construct highly functionalized and fused ring systems and (ii) gem-difluoroolefins bearing a nucleophilic center on the carbon δ to the flourines undergo intramolecular substitution for the fluorine via "anti-Baldwin" 5-endo-trig closures leading to ring-fluorinated heterocycles. Throughout these reactions, fluorines function as an activator of the substrates and a controller over the reaction pathways.

scholarly journals The chemistry of thujone. XV. A versatile route to antifeedants of the polygodial family

1990 ◽  
Vol 68 (10) ◽  
pp. 1698-1708 ◽  
Author(s):  
James P. Kutney ◽  
Krystyna Piotrowska ◽  
Yong-Huang Chen ◽  
Kwok-Ping Norman Cheng ◽  
Zhenyong Gao ◽  
...  
Keyword(s):  
Cyclopropane Ring ◽  
Ring Expansion ◽  
Ring System ◽  
Membered Ring ◽  
Ring Systems ◽  
Tertiary Carbon ◽  
Key Features

Utilizing thujone-derived intermediates, efficient routes to the natural polygodial family of antifeedants as well as novel analogues within this family are described. One of the key features of this study involves the insertion of an oxygen function into a tertiary carbon center adjacent to a cyclopropane ring system thus providing convenient intermediates for subsequent elaboration. An interesting ring expansion of five-membered to six-membered ring systems by means of tri-n-butyltin hydride is also described. Keywords: antifeedants, polygodial, thujone.

Conformation and geometry of cyclopropane rings having π-acceptor substituents: a theoretical and database study

2010 ◽  
Vol 67 (1) ◽  
pp. 94-102 ◽  
Author(s):  
Aurora J. Cruz-Cabeza ◽  
Frank H. Allen
Keyword(s):  
Crystal Structure ◽  
Density Functional ◽  
Cyclopropane Ring ◽  
Computational Techniques ◽  
Functional Theory ◽  
Common Component ◽  
Structure Information ◽  
Energy Profiles ◽  
Cyclopropyl Group ◽  
Experimental Crystal

The 3e′ orbitals of cyclopropane have the correct symmetry to interact with low-lying unoccupied orbitals of π-acceptor substituents and maximum overlap occurs when the two orbital systems are parallel, i.e. when the π-acceptor bisects the ring in projection down the substituent bond. Since the cyclopropyl group is a common component of active pharmaceutical and agrochemical ingredients, it is important that these strong conjugative interactions are well modelled by computational techniques, and clearly represented in experimental crystal structures. Here we show that torsion angle distributions derived from crystal structure data in the Cambridge Structural Database are in excellent correspondence with torsional energy profiles computed using density functional theory (DFT) for a range of substituents: —COOR, —CONR 2, —NO2, vinyl and phenyl. We also show that crystal structure information is invaluable in modelling conformations of compounds that contain multiply substituted rings, where steric interactions require some substituents to adopt energetically disfavoured conformations. Further, conjugative interactions with π-acceptors lead to significant asymmetry in the cyclopropane ring bond lengths and again the experimental and computational results are in excellent agreement. Such asymmetry effects are additive, and this explains bond-length variations in cyclopropane rings bearing two or more π-acceptor substituents.

Comments on collision mechanics in ring systems

1984 ◽  
Vol 75 ◽  
pp. 407-422
Author(s):  
William K. Hartmann
Keyword(s):  
Asteroid Belt ◽  
Surface Erosion ◽  
Surface Layers ◽  
Ring Systems ◽  
Eclipse Observations ◽  
Saturn’S Rings ◽  
Saturn's Rings

ABSTRACTThe nature of collisions within ring systems is reviewed with emphasis on Saturn's rings. The particles may have coherent icy cores and less coherent granular or frosty surface layers, consistent with thermal eclipse observations. Present-day collisions of such ring particles do not cause catastrophic fragmentation of the particles, although some minor surface erosion and reaccretion is possible. Evolution by collisional fragmentation is thus not as important as in the asteroid belt.

Stochasting modeling of planetary ring systems

1984 ◽  
Vol 75 ◽  
pp. 461-469 ◽  
Author(s):  
Robert W. Hart
Keyword(s):  
Maximum Entropy ◽  
Ring System ◽  
The Sun ◽  
Ultimate State ◽  
Interparticle Interactions ◽  
Ring Systems ◽  
First Order ◽  
Planetary Ring ◽  
Insight Into

ABSTRACTThis paper models maximum entropy configurations of idealized gravitational ring systems. Such configurations are of interest because systems generally evolve toward an ultimate state of maximum randomness. For simplicity, attention is confined to ultimate states for which interparticle interactions are no longer of first order importance. The planets, in their orbits about the sun, are one example of such a ring system. The extent to which the present approximation yields insight into ring systems such as Saturn's is explored briefly.

Sulfhydryl bond formation is a prerequisite for proper cycling of centrosomes and chromosomes in mammalian tissue culture cells

1993 ◽  
Vol 51 ◽  
pp. 342-343
Author(s):  
Heide Schatten ◽  
Neidhard Paweletz ◽  
Ron Balczon
Keyword(s):  
Tissue Culture ◽  
Cell Cycle Progression ◽  
Group Formation ◽  
Sulfhydryl Group ◽  
Mammalian Tissue ◽  
Mitotic Chromosomes ◽  
Microtubule Network ◽  
Culture Cells ◽  
Tissue Culture Cells ◽  
Transmission Electron

To study the role of sulfhydryl group formation during cell cycle progression, mammalian tissue culture cells (PTK2) were exposed to 100¼M 2-mercaptoethanol for 2 to 6 h during their exponential phase of growth. The effects of 2-mercaptoethanol on centrosomes, chromosomes, microtubules, membranes and intermediate filaments were analyzed by transmission electron microscopy (TEM) and by immunofluorescence microscopy (IFM) methods using a human autoimmune antibody directed against centrosomes (SPJ), and a mouse monoclonal antibody directed against tubulin (E7). Chromosomes were affected most by this treatment: premature chromosome condensation was detected in interphase nuclei, and the structure in mitotic chromosomes was altered compared to control cells. This would support previous findings in dividing sea urchin cells in which chromosomes are arrested at metaphase while the centrosome splitting cycle continues. It might also support findings that certairt-sulfhydryl-blocking agents block cyclin destruction. The organization of the microtubule network was scattered probably due to a looser organization of centrosomal material at the interphase centers and at the mitotic poles.

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