ROTAMERISM DURING DEMETHYLATION OF THE 2,5-DIMETHOXY-2,5-DIMETHYL-3,4-DIPHENYLHEXANES

1954 ◽  
Vol 32 (8) ◽  
pp. 729-743 ◽  
Author(s):  
J. G. Smith ◽  
George F Wright
Keyword(s):  
The Other ◽  
Stable Conformation ◽  
Carbon Bond ◽  
Other Hand ◽  
Carbon Carbon Bond ◽  
Central Carbon

The fission of methanol from the diastereomeric 2,5-dimethoxy-2,5-dimethyl-3,4-diphenylhexanes leads to products which are best explained in terms of restriction about the central carbon-carbon bond. As would be expected from its stable conformation the dd,ll diastereomer easily forms the 2,2,5,5-tetramethyl-3,4-diphenyltetrahydrofuran, but the meso diastereomer forms a tetrahydrofuran with difficulty. On the other hand the meso diastereomer readily undergoes Friedel-Crafts types of condensation leading in different media to either 3,3-dimethyl-1-isopropenyl-2-phenylindane, 3,3-dimethyl-1-isopropyl-2-phenylindene or 5,5,10,10-tetramethyl-4b,5,9b, 10-tetrahydroindeno[2,1-α]-indene. These indenes are the expected products from a consideration of the conformation of the meso-dimethoxydimethyldiphenylhexane which is most free from steric restriction.

The reaction of Sodium Acetylide with Benzil and related compounds

1956 ◽  
Vol 9 (3) ◽  
pp. 391 ◽  
Author(s):  
J Cymerman-Craig ◽  
M Moyle ◽  
P Rowe-Smith ◽  
PC Wailes
Keyword(s):  
Liquid Ammonia ◽  
Carbon Bond ◽  
Carbon Carbon Bond ◽  
Central Carbon ◽  
Related Compounds

Attempted condensation of benzil and benzoin with sodium acetylide in liquid ammonia caused fission of the central carbon-carbon bond of these substances, giving 3-phenylprop-1-yn-3-ol. Condensation of α-bromodeoxyanisoin with the same reagent gave several non-acetylenic products which have been identified.

The Conformation of Some 1,1,2,2-Tetraacylethanes in the Solid-State: Crystal-Structures of 1,1,2,2-Tetrabenzoylethane, 1,2-Diacetyl-1,2-Dibenzoylethane and 1,1,2,2-Tetraethoxycarbonylethane

1986 ◽  
Vol 39 (11) ◽  
pp. 1811 ◽  
Author(s):  
JR Cannon ◽  
VA Patrick ◽  
AH White
Keyword(s):  
Solid State ◽  
Least Squares ◽  
Crystal Structures ◽  
X Ray Diffraction ◽  
Keto Form ◽  
Carbon Bond ◽  
X Ray ◽  
Carbon Carbon Bond ◽  
Central Carbon ◽  
Least Squares Techniques

The crystal structures of 1,1,2,2-tetrabenzoylethane (3), 1,2-diacetyl- 1,2-dibenzoylethane (4) and 1,1,2,2-tetraethoxycarbonylethane (tetraethyl ethanetetracarboxylate ) (5) have been determined by X-ray diffraction from diffractometer data at 295 K and were refined by least-squares techniques to residuals of 0.050 (1077 'observed' reflections), 0.056 (3020) and 0.041 (480), respectively. Crystals of (3) are triclinic, Pī , Z 1, a 6.145(2), b 9.002(3), c 11.261(3) Ǻ; α 101.91(3), β 91.88(3), γ 105.94(3)°. Crystals of (4) are also triclinic, Pī , Z 2, a 17.119(5), b 7.210(1), c 7.175(2) Ǻ, α 89.59(2), β 72.92(2), γ 87.87(2)°. Crystals of (5) are tetragonal, P42/n, Z 4, a 17.748(6), c 5.515(1)Ǻ. In the solid state each compound exists in the keto form which adopts the antiperiplanar conformation about the central carbon-carbon bond.

Étude cinétique de l'ouverture thermique de la liaison C—C d'aziridines et d'époxydes dipôles-1,3 potentiels: I. Méthode d'étude expérimentale

1985 ◽  
Vol 63 (8) ◽  
pp. 2245-2252 ◽  
Author(s):  
Aïcha Derdour ◽  
Fernand Texier
Keyword(s):  
Rate Constants ◽  
Heterocyclic Compounds ◽  
The Other ◽  
Azomethine Ylide ◽  
Carbon Bond ◽  
Experimental Rate ◽  
Carbon Carbon Bond ◽  
Kinetic Treatment

The thermolysis of the 2-cyanoaziridines (1), 2-alkoxycarbonylaziridines (2), 2-arylaziridines (3), and 2,2-dicyano-3-aryloxiranes (4) leads to a rupture of the carbon –carbon bond yielding an azomethine ylide and the ylide of a carbonyl. The reaction of these ylides of azomethine with methyl acetylene dicarboxylate (MADC) leads to the formation of a 3-pyroline, which is transformed, according to the substituants, to a 2-pyrroline or to pyrrole. The addition of the ylides of carbonyl leads to the formation of dihydrofurans. Through the kinetic treatment of the addition of these heterocyclic compounds (1 to 4) to MADC, it is possible to determine the rate constants for the opening of the C—C bond (k1). In the case of the aziridines 1, the rates have been determined by ir while hplc has been used in the other cases. Relative to the heterocyclic compounds, the order of the experimental rate constants (kex) is always equal to one. In the cases of theN-cyclohexyl-2-cyano-3-alkylaziridines and of the N-cyclohexyl-2-carbomethoxy-3-phenylaziridine, kex varies with the concentration of MADC and this implies that the rate constants for the cycloaddition of the ylide of azomethine and its reclosing to give aziridine are similar. In the other cases, kex is independent of the concentration of MADC and this implies that the heterocyclic compounds are slowly transformed into 1,3-dipoles, followed by a rapid cycloaddition, [Formula: see text]. [Journal translation]

Activation of a Carbon–Carbon Bond in Internal Alkynes: Vinylidene Rearrangement of Disubstituted Alkynes at an Ir Complex

Synlett ◽  
2017 ◽  
Vol 29 (06) ◽  
pp. 727-730 ◽  
Author(s):  
Youichi Ishii ◽  
Takuya Kuwabara ◽  
Shuhei Takamori ◽  
Satoshi Kishi ◽  
Takahiro Watanabe ◽  
...  
Keyword(s):  
Carbon Atom ◽  
Metal Center ◽  
The Other ◽  
Carbon Bond ◽  
13C Labeling ◽  
Carbon Carbon Bond ◽  
Internal Alkynes ◽  
Selective Formation

Reactions of [Cp*Ir(PPh3)Cl2] with various internal acyl­alkynes in the presence of NaBArF 4 resulted in the selective formation of iridacycles via vinylidene rearrangement. 13C-labeling experiments revealed that the acyl group selectively migrates to the other acetylenic carbon atom. This trend is the same as that in the vinylidene rearrangement of internal alkynes at a group 8 metal center.

Carbon−Carbon Bond Formation by Electrophilic Addition at the Central Carbon of the μ-η3-Allenyl/Propargyl Ligand on the Pd−Pd Bond

2001 ◽  
Vol 123 (14) ◽  
pp. 3223-3228 ◽  
Author(s):  
Sensuke Ogoshi ◽  
Takuma Nishida ◽  
Ken Tsutsumi ◽  
Motohiro Ooi ◽  
Tsutomu Shinagawa ◽  
...  
Keyword(s):  
Bond Formation ◽  
Electrophilic Addition ◽  
Carbon Bond ◽  
Carbon Carbon Bond ◽  
Central Carbon
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