State-of-the-art atropisomeric MeOBIPHEP ligands, also referred to as MeO-BIPHEP, originally developed by Roche, have an extraordinarily broad performance profile for many synthetic applications due to their modular ligand design. In many respects, the catalytic profile of the MeOBIPHEP ligands is rather similar to that of other atropisomeric diphosphines such as BINAP and its many analogs.1–4 The nature of the PR2 group strongly influences the catalytic performance of the metal complexes, and the ligands available in research quantities from Sigma-Aldrich represent examples with different steric bulk.
The Krische group reported on the enantioselective Rh-catalyzed reductive coupling of acetylene to aldehydes to α-ketoesters using 29510 to yield the corresponding diene alcohols in good yields and enantioselectivities (1st eq.). The Wiedenhoefer group reported on the intramolecular asymmetric hydroarylation of 2-(4-pentenyl)indoles in moderate to good yield with up to 90% ee catalyzed by a 1:1 mixture of dichloro platinum complex and (S)-3,5-t-Bu-4-MeO-MeOBIPHEP 29511 (2nd eq.). Pregosin and co-workers reported a dramatic improvement of enantioselection in the Pd-catalyzed Heck reaction of aryl triflates to 2-substituted dihydrofuranes when using (R)-3,5-t-Bu-MeOBIPHEP 29524 (3rd eq.).
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