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|Title:||Palladium-complex-promoted asymmetric synthesis of stereoisomeric P-chiral pyridylphosphines via an unusual exo-endo stereochemically controlled asymmetric diels-alder reaction between 2-vinylpyridine and coordinated 3,4-dimethyl-1-phenylphosphole|
|Citation:||He, G.,Loh, S.-K.,Vittal, J.J.,Mok, K.F.,Leung, P.-H. (1998-08-31). Palladium-complex-promoted asymmetric synthesis of stereoisomeric P-chiral pyridylphosphines via an unusual exo-endo stereochemically controlled asymmetric diels-alder reaction between 2-vinylpyridine and coordinated 3,4-dimethyl-1-phenylphosphole. Organometallics 17 (18) : 3931-3936. ScholarBank@NUS Repository.|
|Abstract:||The organopalladium complex containing ortho-metalated (S)-(1-(dimethylamino)ethyl)-naphthalene as the chiral auxiliary has been used successfully to promote the asymmetric [4 + 2] Diels-Alder reaction between 3,4-dimethyl-1-phenylphosphole and 2-vinylpyridine. The pyridyl group in the resulting phosphanorbornene cycloadducts can be located stereospecifically in the exo or endo position by controlling the electronic properties of the organopalladium promoter. In the exo-cycloaddition process, the P-N bidentate ligand (-)-2-[(1α,2α(S),4α,7S)-5,6-dimethyl-7-phenyl-7- phosphabicyclo[2.2.1]hept-5-ene-2-yl]pyridine was produced stereoselectively. In the endo-cycloaddition process, however, a pair of separable diastereomeric palladium template complexes containing the naphthylamine auxiliary and the enantiomeric forms of 2-[(1α,2β(R/S),4β,7(R/S)-5,6-dimethyl-7-phenyl-7-phosphabicyclo- [2.2.1]hept-5-ene-2-yl]pyridine were obtained. In these diastereomeric complexes, the endocycloadducts coordinated on palladiun as monodentate ligands via only their phosphorus donor atoms. The pyridyl-nitrogen atoms are not involved in metal complexation. The absolute configurations and the coordination properties of the exo- and endo-pyridylphosphines have been established by single-crystal X-ray analyses.|
|Appears in Collections:||Staff Publications|
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