- Preparation of aminophosphines
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Disclosed is a process for the preparation of phosphine-aminophosphines that are useful in the formation of catalysts useful in carrying out a wide variety of reactions such as asymmetric hydrogenations, asymmetric reductions, asymmetric hydroborations, asymmetric olefin isomerizations, asymmetric hydrosilations, asymmetric allylations, asymmetric conjugate additions, and asymmetric organometallic additions. The process comprises the steps of (1) contacting a compound of formula 2 [in-line-formulae]R2P—L—NHR3??2[/in-line-formulae] with phosphorus trihalide PX3 in the presence of an inert, organic solvent and an acid acceptor to produce intermediate compound having formula 3 (2) contacting intermediate compound 3 with a reactant having the formula R1—M1, R2—M1 or a mixture thereof.
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Page/Page column 18-19
(2010/02/11)
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- A versatile synthesis of phosphine-aminophosphine ligands for asymmetric catalysis
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A new and versatile synthesis of phosphine-aminophosphine ligands allows the incorporation of a wide range of nitrogen and phosphorus substituents into these ligands, several of which exhibit improved properties for rhodium-catalyzed asymmetric hydrogenation reactions. This synthesis also allows the preparation of mixed phosphine-phosphoramidite species.
- Boaz, Neil W.,Ponasik Jr., James A.,Large, Shannon E.
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p. 2063 - 2066
(2007/10/03)
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- Synthesis and application of phosphinoferrocenylaminophosphine ligands for asymmetric catalysis
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(Chemical Equation Presented) A new class of bidentate ligands utilizing a phosphine-aminophosphine structure has been prepared on a ferrocenylethyl backbone in a straightforward and scalable fashion from acetylferrocene. The unique property of the α-ferrocenyl carbonium ion that allows the replacement of a variety of "leaving groups" with retention of configuration greatly facilitates the synthesis, and a number of ligands have been prepared by varying the nitrogen and phosphorus substituents on the aminophosphine. These readily prepared phosphinoferrocenylaminophosphines, known as BoPhoz ligands, show surprising hydrolytic and air stability, with no degradation after 3 years open to the air. The rhodium complexes of these ligands show exceedingly high enantioselectivities (generally > 95% ee) and activities often in excess of 50 000 catalyst turnovers per hour for the asymmetric hydrogenation of a wide variety of dehydro-α-amino acid and itaconic acid derivatives. They also show high activity and good to excellent enantioselectivity for the hydrogenation of a number of α-ketoesters.
- Boaz, Neil W.,Mackenzie, Elaine B.,Debenham, Sheryl D.,Large, Shannon E.,Ponasik Jr., James A.
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p. 1872 - 1880
(2007/10/03)
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- The preparation of enantiomerically pure cyclopropylalanine
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Single enantiomer cyclopropylalanine (>99.9% ee) and various derivatives were prepared using an asymmetric hydrogenation approach with a rhodium catalyst based on the methyl BoPhoz ligand. N-Boc cyclopropylalanine benzyl ester was the preferred derivative
- Boaz, Neil W.,Debenham, Sheryl D.,Large, Shannon E.,Moore, Mary K.
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p. 3575 - 3580
(2007/10/03)
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- Synthesis of β-Cyclopropylalanines by Photolysis of Diacyl Peroxides
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(Matrix presented) Photolysis at 254 nm of neat (no solvent) unsymmetrical diacyl peroxides derived from cyclopropane carboxylic acids and L-aspartic acid generates protected β-cyclopropylalanines in reasonable yields. Orthogonally protected 3-(trans-2-am
- Jain, Rajendra P.,Vederas, John C.
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p. 4669 - 4672
(2007/10/03)
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- Phosphinoferrocenylaminophosphines as novel and practical ligands for asymmetric catalysis
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(Matrix Presented) A new series of ligands with a novel phosphine-aminophosphine ligation design as depicted in structure 1 has been prepared on a ferrocenylethyl backbone. These BoPhoz ligands of structure 2 have afforded exceedingly high activity and enantioselectivity in the rhodium-catalyzed asymmetric hydrogenation of dehydro-α-amino acid derivatives, itaconic acids, and α-ketoesters. These air-stable ligands are readily prepared from cost-effective and non-pyrophoric intermediates.
- Boaz, Neil W.,Debenham, Sheryl D.,Mackenzie, Elaine B.,Large, Shannon E.
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p. 2421 - 2424
(2007/10/03)
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