作者:Evgueni Gorobets、Guang-Ri Sun、Bronwen M.M. Wheatley、Masood Parvez、Brian A. Keay
DOI:10.1016/j.tetlet.2004.03.073
日期:2004.4
A series of optically pure 3,3'-bis(RO)-MeO-BIPHEP derivatives are prepared and used in palladium catalyzed asymmetric transformations. The phosphine oxide of (+/-)-5 is prepared in four steps from p-methoxyphenol and resolved using the novel resolving reagent chloro((L)-menthoxy)dimethylsilane. Subsequent conversions provide catalysts 8 and 9. Ligands 6, 7 and 10 are prepared in six steps from p-methoxyphenol and the phosphine oxides of 6 and 7, and 10 are resolved using di-p-toluoyl- and dibenzoyl-(L)-tartaric acid, respectively. (R)-3,3'-Bispivalate 8 is superior to the other catalysts in asymmetric Heck reaction with 2,3-dihydrofuran while (R)-(+)-bis(tolyloxy) 10 and (+)-(R)-sugar derivative 9 are better in the Pd-catalyzed polyene cyclization; however, the absolute sense of chirality in the product from the polyene cyclization was reversed to that obtained when (R)-(+)BINAP and (R)-(+)-MeO-BIPHEP were used. (C) 2004 Elsevier Ltd. All rights reserved.