Palladium-Catalyzed Enantioselective Conjugate Addition of Arylboronic Acids

Abstract

[reaction: see text] The first asymmetric palladium-catalyzed conjugate addition of arylboronic acids to alpha,beta-unsaturated aldehydes, ketones, and esters is described. For cyclic substrates, excellent chemo-, regio-, and enantioselectivities are achieved when a Pd(O2CCF3)2/DuPHOS catalyst is applied.

Palladium(II)-Catalyzed Alkene Functionalization via Nucleopalladation: Stereochemical Pathways and Enantioselective Catalytic Applications

“…Bisphosphine ligands were also effective for the enantioselective 1,4-addition of aryl boronic acids 152 and arylsiloxanes to α,β-unsaturated ketones. 153 With a very simple Pd(TFA) 2 /Me-DuPhos catalyst in aqueous THF, Minnard and co-workers showed that a variety of aryl boronic acids and α,β-unsaturated ketones were coupled with good yields and excellent enantioselectivity (Scheme 93).…”

Rhodium‐ and Palladium‐Catalyzed Asymmetric Conjugate Additions

“…It was proposed that an additional role of HBF 4 was to accelerate the rate of exchange between aldehyde and their corresponding hydrates, which is their favored form in aqueous solvents (Scheme 1.83) [248]. Minnaard and coworkers reported that the Pd-catalyzed ECA is efficiently catalyzed by Pd(OCOCF 3 ) 2 as a catalyst precursor [249]. In this case, an active cationic Pd species generated from Pd(OCOCF 3 ) 2 and (R,R)-Me-duphos (L51) proved to be the most effective ligand.…”

Palladium‐Catalyzed Asymmetric Conjugate Addition of Arylboronic Acids to Heterocyclic Acceptors

“…[1] These processes often utilize easily-handled, air- and water-stable boron nucleophiles that render these reactions highly tolerant of oxygen and moisture. [2] Recently, our group disclosed the asymmetric conjugate addition of arylboronic acids to cyclic enones facilitated by a palladium catalyst derived in situ from palladium(II) trifluoroacetate and a chiral pyridinooxazoline (PyOX) ligand ( 5 ). [3] Notably, our catalyst system was generally applicable for 5-, 6-, and 7-membered carbocyclic enones.…”