Using chiral phosphoramidite ligand (S,R,R)-L1 in the conjugate addition to acyclic nitroalkenes for the first time, we obtained enantioselectivities up to 98%. The use of acyclic substrates with different dialkylzinc reagents provides a catalytic enantioselective route to (functionalized) beta2-amino aldehydes, acids, and alcohols.

Using a combination of chiral monodentate phosphoramidite ligands in the rhodium-catalyzed conjugate addition of boronic acids to three different substrates, we have shown for the first time that the ligand combination approach is applicable for C−C bond formation. Chiral catalysts based on hetero-combinations of ligands are found to be more effective than the homo-combinations. 31 P NMR experiments show that the hetero-combinations are formed in excess over the homo-combinations.

The use of phosphoramidite ligands in the rhodium-catalyzed asymmetric conjugate addition of potassium organotrifluoroborates to various enones in the absence of water is described. A systematic search for effective catalysts has been performed by use of high-throughput screening methods. Initially, we have screened reaction conditions, catalyst precursors, and focused ligand libraries. In the next stage we have used the monodentate ligand combination approach, and finally we have made a library of 96 different phosphoramidites by parallel synthesis in the robot (instant ligand libraries) and have tested these in the vinylation of cyclohexenone (up to 88% enantiomeric excess, ee) and 4-phenyl-3-buten-2-one (up to 42% ee). Arylation of cyclohexenone by use of potassium phenyltrifluoroborate gave 3-phenylcyclohexanone with 99% ee.

One-pot multi-substrate enantioselective conjugate addition of diethylzinc to nitroalkenes Duursma, A.; Minnaard, A.J.; Feringa, B.L. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. AbstractÐA multi-substrate approach is used in the copper-phosphoramidite catalyzed enantioselective conjugate addition of diethylzinc to nitroalkenes, using up to nine different nitroalkenes in a one pot procedure. The 18 products (9 times 2 enantiomers of nine different nitroalkanes) can be analyzed by chiral CG in a single run since on overlap in the peaks is observed. The obtained enantioselectivities are amongst the highest reported so far for the catalytic 1,4-addition of dialkylzinc reagents to nitroalkenes. q