Umicore Precatalysts for Asymmetric Reactions

Precatalysts for Asymmetric and Cross-Coupling Catalysis

Introduction
Sigma-Aldrich and Umicore are happy to offer a series of precatalysts for asymmetric catalysis and Pd based cross-coupling catalysis. Our partnership with Umicore allows us to offer a portfolio of metal complexes with batch-to-batch consistency for a plethora of catalytic reactions. Twenty different precatalyst complexes are available, providing access to a hundred different catalytic reactions.

Representative Application
Catalytic hydrogenation is a powerful and effective method used for the reduction of organic molecules. Krische and co-workers have developed methods to utilize this catalytic reaction to generate C–C coupling. After extensive studies done using Rhodium as a precatalyst, Krische and co-workers realized the limitations of Rhodium to catalyze C–C bond forming hydrogenation of only conjugated alkynes. To circumvent these limitations, the utilization of another catalyst was necessary. To expand the scope, Ngai et al. investigated the potency of Ir(COD)₂BARF for this transformation. These new complexes proved to be very active with nonconjugated, alkyl-substituted alkynes. In a typical reaction,
Ir(COD)₂BARF, DPPF ligand and triphenylacetic acid are used to catalyze the coupling hydrogenation of 3-hexyne with a variety of α-ketoesters to yield α-hydroxyesters in good yields.

Reference: Ngai, W.-Y. et al. J. Am. Chem. Soc. 2007, 129, 280.

Scheme 1: Iridium catalyzed C–C bond forming hydrogenation

Product Information

Product #	Product Name	Structure	Add to Cart
683353	Bis(2-methylallyl)(1,5-cyclooctadiene)ruthenium(II)
693774	Bis(cyclooctadiene)iridium(I) tetrakis(3,5-bis(trifluoromethyl)phenyl)
683086	(Acetylacetonato)(1,5-cyclooctadiene)iridium(I)
683094	Bis(1,5-cyclooctadiene)diiridium(I) dichloride
683108	(Acetylacetonato)(1,5-cyclooctadiene)rhodium(I)
683116	(Acetylacetonato)(norbornadiene)rhodium(I)
683132	Chloro(1,5-cyclooctadiene)rhodium(I) dimer
683140	Bis(1,5-cyclooctadiene)rhodium(I) tetrafluoroborate
683159	Bis(1,5-cyclooctadiene)rhodium(I) trifluorosulfonate
683167	Bicyclo[2.2.1]hepta-2,5-diene-rhodium(I) chloride dimer
683175	Bis(norbornadiene)rhodium(I) tetrafluoroborate
686891	Pentamethylcyclopentadienylrhodium(III) chloride dimer
683183	(Acetylacetonato)dicarbonylrhodium(I)
683191	Dichloro(1,5-cyclooctadiene)ruthenium(II) polymer
683205	Diiodo(p-cymene)ruthenium(II) dimer
683213	Dichloro(p-cymene)ruthenium(II) dimer
683221	Benzeneruthenium(II) chloride, dimer
683396	Allylpalladium(II) chloride dimer
683388	Palladium(II) acetylacetonate
683124	Palladium(II) acetate	Pd(OAc)2
683345	Tris(dibenzylideneacetone)dipalladium(0)	Pd2dba3

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