Antarafacial Mediation of Oxygen Delivery by a Phenylsulfinyl Group in the Epoxidation of Proximal Double Bonds: Intramolecular Trapping of an Early Pummerer Intermediate with Stereoelectronic Control
Yandong Zhang
Jun Hee Lee
Samuel J. Danishefsky
10.1021/ja1107707.s002
https://acs.figshare.com/articles/dataset/Antarafacial_Mediation_of_Oxygen_Delivery_by_a_Phenylsulfinyl_Group_in_the_Epoxidation_of_Proximal_Double_Bonds_Intramolecular_Trapping_of_an_Early_Pummerer_Intermediate_with_Stereoelectronic_Control/2695591
Stereospecific intramolecular antarafacial epoxidation of a double bond via an early Pummerer reaction intermediate has been demonstrated. The intermediate is presumably generated via trifluoroacetylation of a sulfoxide precursor. Ionization of trifluoroacetate would formally generate a dipositive “sulfenium” equivalent. This species attacks an otherwise unactivated, proximal olefinic linkage in an antiperiplanar fashion, with trifluoroacetate serving as the nucleophile. Proposed mechanistic intermediates were characterized structurally (in several cases by crystallographic means) and shown to serve as precursors en route to the final antarafacial epoxides. The sense of the cyclization seems to be driven by principles inherent in Markovnikov’s rule.
2011-02-02 00:00:00
dipositive
sulfenium
Oxygen Delivery
nucleophile
species attacks
Pummerer Intermediate
Intramolecular Trapping
Ionization
Stereoelectronic ControlStereospecific intramolecular antarafacial epoxidation
cyclization
intermediate
sulfoxide precursor
Epoxidation
antarafacial epoxides
Markovnikov
Antarafacial Mediation
equivalent
Phenylsulfinyl Group
principle
Pummerer reaction
trifluoroacetate
trifluoroacetylation
antiperiplanar fashion
Proximal Double Bonds
unactivated
olefinic linkage
bond