Enantio- and diastereoselective hetero-Diels–Alder reactions between 2-aza-3-silyloxy-1,3-butadienes and aldehydes catalyzed by chiral dirhodium(ii) carboxamidates
The first catalytic asymmetric hetero-DielsâAlder reaction between 2-aza-3-silyloxy-1,3-butadienes and aldehydes is described. With dirhodium(II) tetrakis[N-benzene-fused-phthaloyl-(S)-piperidinonate], Rh2(S-BPTPI)4, the cycloaddition reaction proceeded exclusively in an endo mode to give all-cis-substituted 1,3-oxazinan-4-ones in high yields with up to 98% ee.
(4+3) Annulation of Donor‐Acceptor Cyclopropanes and Azadienes: Highly Stereoselective Synthesis of Azepanones
作者:Stefano Nicolai、Jérôme Waser
DOI:10.1002/anie.202209006
日期:2022.9.5
Azepanones are important and widespread seven-membered heterocycles, but their synthesis is challenging. A convergent method to access these scaffolds was developed relying on a (4+3) annulation reaction of azadienes and donor-acceptor cyclopropanes. Good to excellent yields and high diastereoselectivity were achieved using Yb(OTf)3 as the catalyst. Asymmetric induction was possible with Cu(OTf)2 in