Addition of arenesulphenyl chlorides to 2-methylenebicyclo[2.2.1]hept-5-ene: effect of increasing electron demand upon the rate and product determining transition states

1980 ◽  
Vol 58 (10) ◽  
pp. 1021-1029 ◽  
Author(s):  
Dennis G. Garratt ◽  
Pierre L. Beaulieu ◽  
Veronique M. Morisset

The rates and products of addition of a series of sixteen arenesulphenyl chlorides to 2-methylenebicyclo[2.2.1]hept-5-ene, 7, and the E, Z isomeric 2-ethylidenebicyclo[2.2.1]hept-5-enes, 8 and 9, have been determined in methylene chloride solution. The major species from attack on 7 is always endo-3-arylthio-1-chloromethyltricyclo[2.2.1.02,6]heptane, the product of exo attack upon the endocyclic double bond with homoallylic participation of the exocyclic π system. No evidence was found for initial electrophilic attack upon the exocyclic double bond.

1979 ◽  
Vol 57 (1) ◽  
pp. 119-127 ◽  
Author(s):  
Dennis G. Garratt ◽  
Pierre Beaulieu

The reaction of 2,4-dinitrobenzenesulphenyl chloride with eight alkyl 1,3-disubstituted allenes in methylene chloride solution has been investigated. In contrast to earlier reports, attack by sulphur is found to occur exclusively at the central allenic carbon. The direction of approach of sulphenyl chloride leads preferentially to the formation of the E isomers in accord with the concept of steric approach control. The ratio of E to Z alkene is found to increase as the bulk of the substituent group cis to the arylthio group increases. We observe, however, very little regioselectivity with respect to which of the mutually perpendicular π bonds of the allene system is attacked, suggesting the presence of an effective mechanism for transmission of inductive effects to the more distant double bond.


1996 ◽  
Vol 74 (11) ◽  
pp. 2331-2339 ◽  
Author(s):  
Sean R. Klopfenstein ◽  
Constanze Kluwe ◽  
Kristin Kirschbaum ◽  
Julian A. Davies

The binuciear palladium(I) complex, [Pd2Cl2(μ-dppm)2] (dppm = bis(diphenylphosphino)methane), has been shown to react with bis(diethylamino)acetylene, Et2NC≡CNEt2, in methylene chloride solution to yield two isolable products, the known methylene-bridged complex, [Pd2Cl2(μ-CH2)(μ-dppm)2], and hexakis(diethylamino)benzene, C6(NEt2)6, both of which have been characterized crystallographically. The source of the bridging methylene group in [Pd2Cl2(μ-CH2)(μ-dppm)2] has been shown to be the methylene chloride solvent. A mechanism that accounts for the formation of the two isolable products is proposed. The complex, [Pd2Cl2(μdmpm)2] (dmpm = bis(dimethylphosphino)methane), was similarly found to react with Et2NC≡NEt2 in methylene chloride solution to yield [Pd2Cl2(μ-CH2)(μ-dmpm)2], which was identified spectroscopically. Key words: acetylene, palladium, cyclooligomerization, aminoacetylene, hexakis(diethylamino)benzene.


1968 ◽  
Vol 46 (12) ◽  
pp. 2147-2157 ◽  
Author(s):  
R. J. Gillespie ◽  
J. S. Hartman

1H and 19F n.m.r. studies of BF3 adducts of some simple methyl ketones in methylene chloride solution have led to the following conclusions. (1) Only 1:1 adducts are formed which are not appreciably dissociated. (2) The down-field shifts of the proton resonances caused by complexation with BF3 are essentially independent of the ketone and depend only on the distance of the proton from the carbonyl group. (3) BF3 exchange is rapid on the n.m.r. time scale at room temperature, but the exchange process can be slowed sufficiently by lowering the temperature that separate signals due to free and complexed species can be observed. (4) Collapse of the 10B−11B isotope shift with increasing temperature showed that a second chemical exchange process, which exchanges fluorine among boron atoms, occurs in addition to the process of rapid breaking and re-forming of donor–acceptor bonds. A possible mechanism for this fluorine scrambling reaction is discussed.


1981 ◽  
Vol 59 (6) ◽  
pp. 927-934 ◽  
Author(s):  
Dennis G. Garratt ◽  
Pierre L. Beaulieu ◽  
Veronique M. Morisset

The reaction of benzeneselenenyl chloride with twenty-two propargyl alcohols in methylene chloride solution is reported. Products of both Markownikoff and anti-Markownikoff regiochemistry are formed in an anti stereospecific manner. The regioselectivity or specificity is found to be very dependent upon the nature of the substituents geminal to the alcoholic moiety. In general the presence of bulky substituents geminal to the alcoholic moiety tend to favour formation of the anti-Markownikoff adduct under conditions of kinetic control. The Markownikoff adducts are found to be favoured thermodynamically.


2003 ◽  
Vol 42 (15) ◽  
pp. 4513-4515 ◽  
Author(s):  
Oren P. Anderson ◽  
Agnete la Cour ◽  
Andrew Berg ◽  
Andrew D. Garrett ◽  
Mark Wicholas

1999 ◽  
Vol 54 (1) ◽  
pp. 113-116 ◽  
Author(s):  
J. Nolte ◽  
P. Neubauer ◽  
H. Vogt ◽  
M. Meisel

Tris(di-n-propylamino)-p-bromobenzylphosphonium bromide [(C3H7)2N]3PCH2C6H4Br+- Br- (1) has been prepared by the reaction of tris(di-n-propylamino)phosphine with p-bromobenzylbromide in methylene chloride. The colorless crystals are monoclinic, space group P21, Z = 2, a = 930.2(3), b = 1501.2(3), c = 1093.5(2) pm, β = 105,97(4)°. The lattice contains Br- anions and [(C3H7)2N]3PCH2C6H4Br+ cations. [(C3H7)2N]3PCH2C6H4Br+Br- (2) has been obtained by treating 1 with equimolar quantities of elemental bromine in methylene chloride solution. The yellow-red crystals of 2 are triclinic, space group P1̄, Z = 2, a = 1069.5(3), b = 1267.7(7), c = 1273.7(3) pm, α= 87.27(3), β = 82,67, γ = 67.15°, and consist of [(C3H7)2N]3PCH2C6H4Br+ cations and linear Br3- anions. The three N atoms in the cations of 2 are planar.


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