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.

scholarly journals Crystal structures of ethyl (2S*,2′R*)-1′-methyl-2′′,3-dioxo-2,3-dihydrodispiro[1-benzothiophene-2,3′-pyrrolidine-2′,3′′-indoline]-4′-carboxylate and ethyl (2S*,2′R*)-5′′-chloro-1′-methyl-2′′,3-dioxo-2,3-dihydrodispiro[1-benzothiophene-2,3′-pyrrolidine-2′,3′′-indoline]-4′-carboxylate

2014 ◽  
Vol 70 (8) ◽  
pp. 94-97 ◽  
Author(s):  
M. P. Savithri ◽  
M. Suresh ◽  
R. Raghunathan ◽  
G. Vimala ◽  
R. Raja ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Dihedral Angle ◽  
Ring System ◽  
Membered Ring ◽  
Equatorial Position ◽  
Ring Systems ◽  
Envelope Conformation ◽  
Extended Conformation ◽  
The Mean

In the title compounds, C22H20N2O4S, (I), and C22H19ClN2O4S, (II), the pyrrolidine rings have twist conformations on the spiro–spiro C—C bonds. In (I), the five-membered ring of the oxindole moiety has an envelope conformation with the spiro C atom as the flap, while in (II) this ring is flat (r.m.s. deviation = 0.042 Å). The mean planes of the pyrrolidine rings are inclined to the mean planes of the indole units [r.m.s deviations = 0.073 and 0.069 Å for (I) and (II), respectively] and the benzothiophene ring systems (r.m.s. deviations = 0.019 and 0.034 Å for (I) and (II), respectively) by 79.57 (8) and 88.61 (7)° for (I), and by 81.99 (10) and 88.79 (10)° for (II). In both compounds, the ethoxycarbonyl group occupies an equatorial position with an extended conformation. The overall conformation of the two molecules differs in the angle of inclination of the indole unit with respect to the benzothiophene ring system, with a dihedral angle between the planes of 71.59 (5) in (I) and 82.27 (7)° in (II). In the crystal of (I), molecules are linkedviapairs of N—H...O hydrogen bonds, forming inversion dimers enclosingR22(14) loops. The dimers are linkedviaC—H...O and bifurcated C—H...O(O) hydrogen bonds, forming sheets lying parallel to (100). In the crystal of (II), molecules are again linkedviapairs of N—H...O hydrogen bonds, forming inversion dimers but enclosing smallerR22(8) loops. Here, the dimers are linked by C—H...O hydrogen bonds, forming ribbons propagating along [010].

scholarly journals Structurally diverse arene-fused ten-membered lactams accessed via hydrolytic imidazoline ring expansion

2017 ◽  
Vol 15 (14) ◽  
pp. 2906-2909 ◽  
Author(s):  
Alexander Sapegin ◽  
Angelina Osipyan ◽  
Mikhail Krasavin
Keyword(s):  
Medicinal Chemistry ◽  
Ring Expansion ◽  
Membered Ring ◽  
Synthetic Methods ◽  
Ring Systems ◽  
New Hire ◽  
Imidazoline Ring

A facile approach to hitherto unknown ten-membered ring systems via a hydrolytic imidazoline ring expansion (HIRE) is described. Medium-sized rings are scarce in the contemporary medicinal chemistry toolbox. The new HIRE strategy broadens the arsenal of synthetic methods to obtain such scaffolds.

PH-funktionelle Phosphane mit α- und β-ständigen 2-Pyridylsubstituenten 2-C5H4N—[CH2]n—PRH (R = H, iPr, tBu, Ph, 2-C5H4N-[CH2]n; n = 1, 2) / PH-Functional Phosphanes with 2-Pyridyl Substituents in α- or β-Position 2-C5H4N —[CH2]n—PRH (R = H, iPr, tBu, Ph, 2-C5H4N-[CH2]n; n = 1,2)

1987 ◽  
Vol 42 (5) ◽  
pp. 579-588 ◽  
Author(s):  
Gerd U. Spiegel ◽  
Othmar Stelzer
Keyword(s):  
Transition Metal ◽  
Transition Metal Complexes ◽  
Chelate Ring ◽  
Ring System ◽  
Membered Ring ◽  
Ring Systems ◽  
H Nmr ◽  
Metal Metal ◽  
Monodentate Ligands ◽  
Metal Bonds

PH-functional phosphanes containing a 2-pyridyl substituent in α- or β-position to phosphorus, e.g. 2-C5H4N - [CH2]n-PRH (R = H, iPr, tBu, Ph; n = 1,2) have been obtained. The reactivity of the PH-groups can be employed for the synthesis of tridentate NPN-hvbrid donors. [2-C5H4N -CH2-CH2]2PR (R = H. Ph). The phosphanes 2-C5H4N-[CH2]n-PRH behave as monodentate ligands in transition metal complexes and form labile chelate ring systems. They may bridge metal-metal bonds to form seven membered ring systems, e.g. Mo2PC3N. The coordination of the N-donor of the ligands 2-C5H4N - [CH2]n-PRH to a transition metal atom is indicated by a lowfield shift and a small 31P - 13C-splitting of the 13C{1H} NMR signal of carbon atom 6 in the pyridin ring system.

Synthetic Approaches to Non-Tropane, Bridged, Azapolycyclic Ring Systems Containing Seven-Membered Carbocycles

Synthesis ◽  
2020 ◽  
Vol 53 (01) ◽  
pp. 65-78
Author(s):  
Daniel R. Griffith ◽  
Aaron H. Shoemaker
Keyword(s):  
Building Blocks ◽  
Short Review ◽  
Ring Expansion ◽  
Membered Ring ◽  
Biologically Active ◽  
Ring Systems ◽  
Ring Expansions ◽  
Carbocyclic Rings ◽  
Synthetic Approaches ◽  
Acyclic Precursor

AbstractThis Short Review highlights various synthetic approaches to bridged azabicyclic ring systems containing seven-membered carbocyclic rings. Such ring systems are common to a number of biologically active natural products. The seven-membered ring in such systems is generally formed in one of four ways: 1) cyclization of an acyclic precursor; 2) ring expansion or rearrangement of a different ring size; 3) cycloaddition; and 4) use of a synthetic building block with the seven-membered ring already present. Representative examples of each approach from both total synthesis and methodological studies are discussed, with an emphasis on work publishedin the last twenty years.1 Introduction2 Cyclization Reactions3 Ring Expansions and Rearrangements4 Cycloadditions5 Strategies Involving Seven-Membered Ring Building Blocks6 Conclusion

scholarly journals 1-(Pyridin-4-yl)-3-(2,4,6-trichlorophenyl)benz[4,5]imidazo[1,2-d][1,2,4]triazin-4(3H)-one

IUCrData ◽  
2016 ◽  
Vol 1 (10) ◽  
Author(s):  
Bassam Abu Thaher ◽  
Dieter Schollmeyer ◽  
Basem Qeshta ◽  
Kanan M. Wahedy ◽  
Ihab M. Almasri ◽  
...  
Keyword(s):  
Title Compound ◽  
Pyridine Ring ◽  
Crystal Packing ◽  
Ring System ◽  
Membered Ring ◽  
Dihedral Angles ◽  
Ring Systems ◽  
Π Interactions ◽  
Compound C ◽  
Centroid Distance

In the title compound, C20H10Cl3N5O, the 13-membered ring system makes dihedral angles of 78.64 (9)° with the trichlorophenyl ring and 62.60 (10)° with the pyridine ring. The crystal packing is dominated by π–π interactions between the 13-membered ring systems [centroid–centroid distance = 3.6655 (11)°].

Some studies on the solvolysis of 1-chloro-1-alkyl cycloalkanes

1980 ◽  
Vol 58 (14) ◽  
pp. 1484-1489 ◽  
Author(s):  
K. Ranganayakulu ◽  
M. Vasumathi Devi ◽  
R. Balaji Rao ◽  
K. Rajeswari
Keyword(s):  
Activation Energy ◽  
Chair Conformation ◽  
Ring System ◽  
Membered Ring ◽  
Energy Contribution ◽  
Ring Systems ◽  
Chair Form ◽  
Carbonium Ion ◽  
Rearrangement Reaction ◽  
Twist Boat

The effect of the bulk of the sidechain on the rate of solvolysis of 1-alkyl cyclopentyl, cyclohexyl, and cycloheptyl chlorides has been studied. With the exception of the t-butyl systems, the ratio of solvolysis rates for the three ring systems falls in a given series. The slower rate of solvolysis in the six-membered ring system may be due to an extra activation energy contribution caused by the conversion of a neutral chair form to the twist boat or half chair conformation, prior to the actual solvolysis. In the case of five- and seven-membered ring systems the formation of an intermediate carbonium ion is sterically favoured (I-strain or eclipsing interaction) consistent with earlier findings. The faster rate of solvolysis of 1-t-butylcycloalkyl chlorides is likely due to a rearrangement reaction where alkyl participation enhances the rate of solvolysis.

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.

ChemInform Abstract: Five-Membered Ring Systems: Thiophenes and Se/Te Analogues

ChemInform ◽  
2009 ◽  
Vol 40 (23) ◽  
Author(s):  
Tomasz Janosik ◽  
Jan Bergman
Keyword(s):  
Membered Ring ◽  
Ring Systems
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