Asymmetric synthesis of a chiral hetero-bidentate As–P ligand containing both As and P-stereogenic centres

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• 作者：Mengtao Ma ; Sumod A. Pullarkat ; Yongxin Li ; Pak-Hing Leung
• 关键词：Asymmetric Diels– ; Alder reaction ; Chiral As– ; P Ligand ; Palladium complex
• 刊名：Journal of Organometallic Chemistry
• 出版年：2008
• 出版时间：1 October 2008
• 年：2008
• 卷：693
• 期：20
• 页码：3289-3294
• 全文大小：455 K

文摘

The organopalladium complex containing ortho-metalated (S)-[1-(dimethylamino)ethyl]naphthalene as the chiral auxiliary has been used as the chiral template to promote the asymmetric cycloaddition reaction between phenyldivinylphosphine and 3,4-dimethyl-1-phenylarsole. The reaction was completed in 1 h at room temperature, with the formation of two isomeric cycloadducts in the ratio 1:3. The major phenylvinylphosphino-substituted asymmetrical hetero-bidentate arsanorbornene ligand with chirality residing on both As and P centers was obtained stereoselectively on the chiral palladium template in moderate yield. The chiral heterobidentate ligand was isolated in its enantiomerically pure form by removal of the chiral auxiliary using concentrated hydrochloric acid and subsequent cleavage from the neutral complex [(As–P)PdCl₂] by using potassium cyanide. Similar to the earlier reported analogous diphenylphosphino-substituted asymmetrical heterobidentate arsanorbornene (As–P) ligand, an arsenic elimination process was also found in the dichloro and dibromo palladium complex whereas the diiodo species did not show similar reactivity, but the corresponding η² diiodo complex could be obtained from the η² dibromo complex by treatment with sodium iodide.