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New ligands and catalysts catalogue now available

Solvias is pleased to announce its newly enhanced catalogue for ligands and catalysts. The portfolio has been further enlarged with new ligand derivatives of successful ligand families and the PFA (1-[1-(Dimethylamino)ethyl]-2-(di-aryl/alkyl-phosphino)ferrocene) ligand family.

These new PFA, Josiphos, POX ((4,5-Dihydro-4-alkyl-2-oxazolyl)-2-(diarylphosphino)ferrocene) and Walphos derivatives represent the next step towards a ligand portfolio that covers the highest possible diversity with regard to electron density and steric bulk. Modularity in ligand design is an important key for a successful lead finding and subsequent optimization in the development of a catalytic reaction. Only the availability of this diversity allows for the evaluation of variations in steric demand and electron density for a certain catalytic reaction and to gain detailed insight into the demands made on the ligand.

After the success story of palladium catalyzed C-X cross-coupling reactions, the research focus seems to have moved towards asymmetric variants of C-X bond forming catalytic transformations and to the employment of cheaper metals such as nickel and copper. In consideration of the seminal work of Hayashi, Kumada and many others, we decided to include PFA ligands (P,N ligands) into our portfolio. For the parent ligand of this family, PPFA (SL-F103-1), very promising results for Ni- and Pd-catalyzed couplings of alkenyl halides with secondary alkyl Grignard reagents as well as with organozinc reagents were reported.[1] Furthermore, reports are available for asymmetric hydrosilylations,[2] the formation of axial chiral binaphthalenes from triorganoindium compounds[3] and boronic acids[4] as well as for copper catalyzed alkylations[5] and [3+2] cycloadditions.[6] By providing electronically and sterically divers members of this ligand family we offer a powerful tool for optimizing such reactions. Our new portfolio comprises PFA ligands ranging from electron poor (SL-F173) to electron rich (SL-F174) and from bulky (SL-F171, SL-F174) to sterically less demanding (SL-F172) properties.

Figure 1. (R)-Derivatives of the PFA ligands.

Similarly, the POX ligand portfolio (P,N ligands) has undergone significant expansion. These ligands have proven high activities and selectivities in Pd-catalyzed asymmetric allylic substitutions[7] and enantioselective intramolecular Heck reactions,[8] Cu-catalyzed conjugative additions of Grignard reagents to enones[9] and [3+2] cycloadditions of azomethine ylides,[10] as well as Ni-catalyzed asymmetric cross-coupling reactions of allylic compounds with Grignard reagents.[11]

Figure 2. (R)-Derivatives of the POX ligands.   

The Walphos ligand portfolio has been extended with the addition of three new members which contain the bulky and electron rich P(tBu)2 group (SL-W012, SL-W029 and SL-W030). These ligands were designed based on related findings from the Josiphos family where ligands with the P(tBu)2 group (e.g. SL-J002 and SL-J009) gave extraordinary results at very low catalyst loadings for C-N,[12] C-S,[13] C-O,[14] Suzuki,[15] Negishi,[16] Kumada cross-coupling reactions.[17] .

Figure 3. (R)-Derivatives of the new Josiphos and Walphos ligands.

[1] Hayashi, Tetrahedron Lett. 1980, 21, 79; Hayashi, Tetrahedron Lett. 1980, 21, 4623; Hayashi, J. Org. Chem. 1983, 48, 2195; Hayashi, JACS 1976, 98, 3718; Hayashi, JACS 1982, 104, 180; Hayashi, Bull. Chem. Soc. Jpn. 1983, 56, 363. [2] Hayashi, JACS 1982, 104, 3772; Hayashi, J. Org. Chem. 1986, 51, 3772. [3] Mosquera, Eur. J. Org. Chem. 2013, 2555. [4] Cammidge, Tetrahedron 2004, 60, 4377. [5] M.-C., Tetrahedron: Asymmetry, 2005, 16, 2531. [6] A. Yamamoto, Tetrahedron Lett. 1989, 30, 375. [7] Ahn, Tetrahedron: Asymmetry, 1997, 8, 1179. [8] Kilroy, J. Mol. Catal. A: Chemical 2003, 196, 65. [9] Stangeland, Tetrahedron 1997, 53, 16503. [10] Gao, Org. Lett. 2005, 7, 4241.  [11] Chung, K.-G, J. Chem. Soc., Perkin Trans. 1 2000, 2725. [12] Green, Org. Lett. 2014, 16, 4388; Vo, JACS 2009, 131, 11049 ; Klinkenberg, JACS 2010, 132, 11830. [13] Fernandez-Rodriguez, Chem. Eur. J. 2010, 16, 2355. [14] Sawatzky, Eur. J. Org. Chem. 2016, 2016, 2444. [15] Yamamoto, Organometallics 2009, 28, 152. [16] Lindhardt, J. Org. Chem. 2009, 74, 135. [17] Limmert, J. Org. Chem. 2005, 70, 9364.

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