70063-97-7Relevant academic research and scientific papers
Effects of Solvent and Additives on the Rearrangement Pathway of the Seyferth Reaction
Lambert, Joseph B.,Boch, Richard J.,Larson, Eric G.
, p. 3054 - 3059 (2007/10/02)
The Seyferth reagent has dual reactivity with electron-deficient alkenes. trans-1,2-Dichloroethene reacts both with the free carbene to give cyclopropane stereospecifically and with a complex between carbene and a second molecule of Seyferth reagent (homogeneous catalysis) to give a rearranged propene.The addition of other materials to the reaction mixture can have a profound effect on the ratio of the two pathways.Good ? donors such as p-xylene decrease the pathway to rearranged propene via the complexed carbene.Such materials thus serve as inhibitors to the process of homogeneous catalysis by forming a competing complex that does not go on to propene but instead reverts to free carbene.The existence of the inhibitor-carbene complex is supported by concentration studies.The presence of insoluble materials such as zinc chloride, on the other hand , serves to decrease the pathway that leads through free carbene to the cyclopropane.Free carbene may react with the surface of the additive and be removed as a reactive species.This latter process would have no effect on carbene previously complexed with the homogeneous catalyst, the Seyferth reagent , which could still proceed to rearranged propene.
REARRANGEMENT AND CATALYSIS IN THE SEYFERTH REACTION.
Lambert,Bosch,Mueller,Kobayashi
, p. 3584 - 3589 (2007/10/02)
The Seyferth reagent PhHgCBr//3 reacts with trans-1,2-dichloroethene to give two major products, trans-1,1-dibromo-2,3-dichlorocyclopropane (C) and 1,1-dibromo-3,3-dichloropropene (P). The stereospecifically formed cyclopropane is consonant with a singlet carbene mechanism, but the rearranged propene requires a second intermediate. Observation that the concentration ratio left bracket P right bracket / left bracket C right bracket is inversely proportional to the concentration of the alkene demonstrates that there are two intermediates, that the cyclopropane comes from the first-formed intermediate, and that the propene comes from the second-formed intermediate.
