High Resolution Nuclear Magnetic Resonance Investigation of the Structure of the Adducts Formed by the Interaction of Benzylidenemalononitriles with Trialkylphosphines

1972 ◽  
Vol 50 (11) ◽  
pp. 1713-1718 ◽  
Author(s):  
C. A. Fyfe ◽  
M. Zbozny
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Carbon Atom ◽  
Substitution Reactions ◽  
Resonance Investigation ◽  
Nuclear Magnetic Resonance Investigation ◽  
Magnetic Resonance Investigation ◽  
Nuclear Magnetic

High resolution n.m.r. has been used to determine unambiguously the structure of the adducts formed by the action of trialkylphosphines on para-substituted benzylidenemalononitriles2 as a zwitterionic species formed by attack of the phosphine on the α-carbon atom of the alkene. The relation of this result to possible mechanisms of nucleophilic alkene substitution reactions is discussed.

Nuclear magnetic resonance investigation of intermediates formed by the action of nucleophiles on substituted stilbenes

1969 ◽  
Vol 47 (13) ◽  
pp. 2331-2342 ◽  
Author(s):  
C. A. Fyfe
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Negative Charge ◽  
Trans Isomers ◽  
Substitution Reactions ◽  
Resonance Investigation ◽  
Nuclear Magnetic Resonance Spectra ◽  
Nuclear Magnetic Resonance Investigation ◽  
Magnetic Resonance Investigation ◽  
Nuclear Magnetic

A nuclear magnetic resonance investigation of the colored species formed by the action of bases on a series of α-cyano-4-nitro-4′-X-stilbenes characterizes these as the intermediate carbanions formed by the addition of base to the β-carbon atom of the double bond. The nuclear magnetic resonance spectra reveal that, whereas there is free rotation about the β-phenyl—Cβ and Cβ—Cα bonds in these adducts, there is restricted rotation around the α-phenyl—Cα bond due to very substantial delocalization of the negative charge into this ring. It has been verified that the same intermediates are formed by the action of bases on either the cis or trans isomers of α-cyano-4-nitrostilbene. The relation of these observations to the theory of alkene nucleophilic substitution reactions is discussed.

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