Deuterium-labeling studies establishing stereochemistry at the oxypalladation step in Wacker-type oxidative cyclization of an o-allylphenol.
The stereochemical pathway (syn or anti) of the oxypalladation step was studied in the palladium(II)-catalyzed Wacker-type cyclization of stereospecifically deuterated 6-(2-hydroxyphenyl)-3-deuteriocyclohexenes, cis-3-d-1 and trans-3-d-1, giving dihydrobenzofuran derivatives. The stereochemistry was determined to be syn in the reaction catalyzed by a dicationic palladium(II) catalyst generated from Pd(MeCN)4(BF4)2 and (S,S)-ip-boxax in the presence of benzoquinone in methanol, while it is mainly anti in the reaction catalyzed by PdCl2(MeCN)2 in the presence of a chloride ion.
Hayashi
Tamio
T
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan. thayashi@kuchem.kyoto-u.ac.jp
Yamasaki
Kaori
K
Mimura
Michihiro
M
Uozumi
Yasuhiro
Y