Allenes in asymmetric catalysis: asymmetric ring opening of meso-epoxides catalyzed by allene-containing phosphine oxides.
نویسندگان
چکیده
Unsymmetrically substituted allenes (1,2-dienes) are inherently chiral and can be prepared in optically pure form. Nonetheless, to date the allene framework has not been incorporated into ligands for asymmetric catalysis. Since allenes project functionality differently than either tetrahedral carbon or chiral biaryls, they may create complementary chiral environments. This study demonstrates that optically active, C(2)-symmetric allene-containing bisphosphine oxides can catalyze the addition of SiCl(4) to meso-epoxides with high enantioselectivity. The epoxide opening likely involves generation of a Lewis acidic, cationic (bisphosphine oxide)SiCl(3) complex. The fact that high asymmetric induction is observed suggests that allenes may represent a new platform for the development of ligands and catalysts for asymmetric synthesis.
منابع مشابه
Asymmetric carbon-carbon bond formation gamma to a carbonyl group: phosphine-catalyzed addition of nitromethane to allenes.
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ورودعنوان ژورنال:
- Journal of the American Chemical Society
دوره 131 30 شماره
صفحات -
تاریخ انتشار 2009