Asymmetric synthesis of a P-chiral heteroditopic PP=S ligand via chiral metal template promoted cycloaddition between 3,4-dimethyl-1-phenylphosphole and its sulfonated analog

摘要

The asymmetric [4+2] Diels-Alder reaction involving 3,4-dimethyl-l-phenylphosphole, DMPP, as the cyclic diene and its P-sulfonated analogue DMPP=S as the dienophile was carried out by utilizing the palladium(II) template complex containing ortho-metalated (R)-(1-(dimethylamino)ethyl)naphthalene as the chiral auxiliary. The reaction proceeded regiospecifically and stereo selectively to give corresponding phosphanorbornene P P=S ligand as the major product. Throughout the cycloaddition reaction, DMPP functions chemoselectively as the cyclic diene whilst DMPP=S assumes the role of dienophile. The absolute stereochemistry of the novel chiral heteroditopic P P=S ligand was established by means of single crystal X-ray diffraction analysis. (c) 2006 Elsevier B.V. All rights reserved.