Enantio- and diastereoselective hetero-Diels–Alder reactions between 4-methyl-substituted Rawal’s diene and aldehydes catalyzed by chiral dirhodium(II) carboxamidates: catalytic asymmetric synthesis of (−)-cis-aerangis lactone
The first catalytic asymmetric hetero-Diels–Alder (HDA) reaction between 3-tert-butyldimethylsilyloxy-1-dimethylamino-1,3-pentadiene (4-methyl-substituted Rawal’s diene) and aldehydes is described. With 3 mol % of dirhodium(II) tetrakis[N-benzene-fused-phthaloyl-(S)-piperidinonate], Rh2((S)-BPTPI)4, the cycloaddition reaction proceeded exclusively in an endo fashion and gave, after a novel sequential