INTRODUCTION

Aladdin Reagents Company is able to offer a range of BINOL-derived chiral phosphoric acids in its asymmetric catalyst/ligand product portfolio. This class of well-established chiral Brønsted acid catalysts has been increasingly used in efficient conversion reactions.

Figure 1. BINOL-derived Chiral Phosphoric Acids

ADVANTAGES

• Alternative to metal catalysts and chiral auxiliaries

• Both enantiomers of the catalyst can be used

• Relatively low catalyst loading (typically 1-5 mol %)

• High selectivity at non-freezing reaction temperatures (-30 to 23 °C)

REPRESENTATIVE APPLICATIONS

Reductive Amination

One of the earliest applications of chiral phosphoric acid catalysis was the metal-free reduction of imines with an organic reducing agent (Hantzsch ester) to give enantiomerically enriched amines.

Rueping (2005), List (2005), MacMillan (2006)

Figure 2. Reductive Amination

Allylation

Enantioselective allylation of aldehydes can be accomplished under very mild conditions in a non-cold (-30 °C) environment.

Antilla (2010)

Figure 3. Allylation

Friedel-Crafts Alkylation

Functionalized indoles and pyrroles in enantiomerically enriched forms can be obtained by asymmetric alkylation reactions.

Terada (2007)

Figure 4. Friedel-Crafts Alkylation

References

1. Rueping M, Sugiono E, Azap C, Theissmann T, Bolte M. 2005. Enantioselective Brønsted Acid Catalyzed Transfer Hydrogenation: Organocatalytic Reduction of Imines. Org. Lett.. 7(17):3781-3783. https://doi.org/10.1021/ol0515964

2. Hoffmann S, Seayad AM, List B. 2005. A Powerful Brønsted Acid Catalyst for the Organocatalytic Asymmetric Transfer Hydrogenation of Imines. Angew. Chem. Int. Ed.. 44(45):7424-7427. https://doi.org/10.1002/anie.200503062

3. Storer RI, Carrera DE, Ni Y, MacMillan DWC. 2006. Enantioselective Organocatalytic Reductive Amination. J. Am. Chem. Soc.. 128(1):84-86. https://doi.org/10.1021/ja057222n

4. Jain P, Antilla JC. 2010. Chiral Brønsted Acid-Catalyzed Allylboration of Aldehydes. J. Am. Chem. Soc.. 132(34):11884-11886. https://doi.org/10.1021/ja104956s

5. Terada M, Sorimachi K. 2007. Enantioselective Friedel-Crafts Reaction of Electron-Rich Alkenes Catalyzed by Chiral Brønsted Acid. J. Am. Chem. Soc.. 129(2):292-293. https://doi.org/10.1021/ja0678166

6. Itoh J, Fuchibe K, Akiyama T. 2008. Chiral Phosphoric Acid Catalyzed Enantioselective Friedel-Crafts Alkylation of Indoles with Nitroalkenes: Cooperative Effect of 3Å Molecular Sieves. Angew. Chem. Int. Ed.. 47(21):4016-4018. https://doi.org/10.1002/anie.200800770

7. He Y, Lin M, Li Z, Liang X, Li G, Antilla JC. 2011. Direct Synthesis of Chiral 1,2,3,4-Tetrahydropyrrolo[1,2-a] pyrazines via a Catalytic Asymmetric Intramolecular Aza-Friedel-Crafts Reaction. Org. Lett.. 13(17):4490-4493. https://doi.org/10.1021/ol2018328

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