A general catalytic oxo-hetero-Diels−Alder reaction for pro-chiral aldehyde and ketone N-oxy-pyridines is presented. The catalytic and asymmetric oxo-hetero-Diels−Alder reaction of electron-rich dienes with N-oxy-pyridine-2-carbaldehyde and ketone derivatives, catalyzed by chiralcopper(II)−bisoxazoline complexes, gives optically active six-membered oxygen heterocycles in moderate to good yields and
Asymmetric Synthesis of Adjacent Tri‐ and Tetrasubstituted Carbon Stereocenters: Organocatalytic Aldol Reaction of an Hydantoin Surrogate with Azaarene 2‐Carbaldehydes
作者:June Izquierdo、Noémie Demurget、Aitor Landa、Tore Brinck、Jose M. Mercero、Peter Dinér、Mikel Oiarbide、Claudio Palomo
DOI:10.1002/chem.201902817
日期:2019.9.20
A bifunctional amine/squaramide catalyst promoted direct aldol addition of an hydantoin surrogate to pyridine 2-carbaldehyde N-oxides to afford adducts bearing two vicinal tertiary/quaternary carbons in high diastereo- and enantioselectivity (d.r. up to >20:1; ee up to 98 %) is reported. Acid hydrolysis of adducts followed by reduction of the N-oxide group yields enantiopure carbinol-tethered quaternary