169776-90-3Relevant academic research and scientific papers
Enantioselective Diels-Alder Reaction Using Chiral Mg Complexes Derived from Chiral 2-2-Alkyl- Or 2-[2-[(Arylsulfonyl)amino]phenyl]-4-phenyl-1,3-oxazoline
Ichiyanagi, Tsuyoshi,Shimizu, Makoto,Fujisawa, Tamotsu
, p. 7937 - 7941 (2007/10/03)
Magnesium complexes derived from (R)-2-[2-[(alkyl- or (R)-2-[2-[(arylsulfonyl)amino]phenyl]-4- phenyl-1,3-oxazolines and methylmagnesium iodide were found to be efficient Lewis acid catalysts for the Diels-Alder reaction of 3-alkenoyl-1,3-oxazolidin-2-one with cyclopentadiene. Chiral ligands were easily prepared from readily available D-phenylglycinol in good yields. The reaction of 3-acryloyl-1,3-oxazolidin-2-one with cyclopentadiene catalyzed by a stoichiometric amount of the Lewis acid gave exclusively the endo-cycloaddition product in up to 92% ee. The sulfonamide group on the chiral ligand strongly influenced the enantiofacial selectivity: the use of a toluene-, benzene-, 1- or 2-naphthalene-, or methanesulfonamide group in the chiral ligand gave the endo-(2R)- cycloaddition product, while a trifluoromethanesulfonamide group predominantly gave its enantiomer, the endo-(2S)-cycloaddition product, in 65% ee. The scope and limitations of the catalytic effect of chiral Mg(II) complexes on the enantioselectivity of the Diels-Alder reaction were investigated. The reaction mechanism of the Mg(II)-catalyzed reaction is also discussed on the basis of the experimental results.
Enantioselective Diels-Alder reaction using chiral Lewis acid prepared from Grignard reagent and a chiral 2-(2-p-toluenesulfonylamino)phenyl-4- phenyloxazoline
Fujisawa,Ichiyanagi,Shimizu
, p. 5031 - 5034 (2007/10/02)
Enantioselective Diels-Alder reaction was conducted successfully using a chiral magnesium complex prepared from Grignard reagent and a chiral 2-(2-p- toluenesulfonyl-amino)phenyl-4-phenyloxazoline derived from easily available D-phenylglycine as a chiral
