O-Ylide and π-Complex Formation in Reactions of a Carbene with Dibenzo and Monobenzo Crown Ethers

2014 ◽  
Vol 118 (32) ◽  
pp. 6230-6238 ◽  
Author(s):  
Pablo A. Hoijemberg ◽  
Robert A. Moss ◽  
David V. Feinblum ◽  
Karsten Krogh-Jespersen
Keyword(s):  
Complex Formation ◽  
Crown Ethers ◽  
Π Complex

ChemInform Abstract: π-Complex Formation and Collapse in Electrophilic Halogenation of Aromatic Substrates.

ChemInform ◽  
1987 ◽  
Vol 18 (47) ◽  
Author(s):  
O. M. E. EL-DUSOUQUI ◽  
K. A. M. MAHMUD ◽  
Y. SULFAB
Keyword(s):  
Complex Formation ◽  
Aromatic Substrates ◽  
Π Complex

Proximity Effect in Arene Pi-Complex Formation

1966 ◽  
Vol 21 (9) ◽  
pp. 823-827 ◽  
Author(s):  
Minoru Tsutsui ◽  
Morris N. Levy
Keyword(s):  
Complex Formation ◽  
Proximity Effect ◽  
Grignard Reagent ◽  
Reaction System ◽  
Coupling Reaction ◽  
Reaction Products ◽  
Hydrogen Elimination ◽  
Trans Stilbene ◽  
Π Complex ◽  
Aryl Grignard Reagent

A proximity effect in arene π-complex formation from the reaction system of an aryl Grignard reagent and anhydrous chromic chloride was investigated. The yields of arene π-complexes and any accompanying reaction products were compared by the systematic variation of the aryl Grignard reagent employed. Phenyl Grignard gave the best yield of π-complex followed by the benzyl, mesityl and β-ethyl phenyl analogues. The styryl and phenylacetylenyl analogues did not form any π-complexes.The coupling reaction of benzyl groups gave a new π-complex, π-bibenzyl-π-toluene chromium, along with toluene, bibenzyl and trans-stilbene.Trans-stilbene was found without forming a trace amount of cis-stilbene. A mechanism for this stereospecific and α-hydrogen elimination coupling reaction is proposed.

π-Complex formation and collapse in electrophilic halogenation of aromatic substrates

1987 ◽  
Vol 28 (21) ◽  
pp. 2417-2420 ◽  
Author(s):  
Osman M.E. El-Dusouqui ◽  
Karima A.M. Mahmud ◽  
Yousif Sulfab
Keyword(s):  
Complex Formation ◽  
Aromatic Substrates ◽  
Π Complex

Acylation of aromatic substrates with ketenes. II. Hammett–Brown studies on substituted aromatic compounds

1980 ◽  
Vol 58 (18) ◽  
pp. 1939-1946 ◽  
Author(s):  
K. R. Fountain ◽  
Pamela Heinze ◽  
Dave Maddex ◽  
Greg Gerhardt ◽  
Paul John
Keyword(s):  
Complex Formation ◽  
Aromatic Compounds ◽  
Benzene Derivatives ◽  
Chloride Complexes ◽  
Line Segments ◽  
Aromatic Substrates ◽  
Π Complex ◽  
Partial Rate ◽  
Inorganic Complexes ◽  
Vinyl Cation

Competition reactions using dimethylketene (DMK) – aluminum chloride complexes on a variety of substituted benzene derivatives gave partial rate factors. The logs of these Pfx values when plotted versus σ+ values gave two line segments of ρ = −6.59 for less active substrates, and ρ = −0.92 for more active substrates. Similar results were found for diphenylketene (ρ = −9.47 and −1.07).These results were rationalized by analogy to vinyl cation alkylations. A pair of π complexes (outer then inner) occur between initial approach of the reagent and final, product-determining π-complex formation. In one of these complexes the C=C bond of the ketene complex may be able to back-bond in a manner similar to that found in inorganic complexes of CO and metals.

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