Highly enantioselective hetero-Diels–Alder reactions between Rawal’s diene and aldehydes catalyzed by chiral dirhodium(ii) carboxamidates

Abstract

The first example of a chiral Lewis acid-catalyzed enantioselective hetero-Diels-Alder (HDA) reaction between 1-dimethylamino-3-silyloxy-1,3-butadiene (Rawal's diene) and aldehydes is described. The cycloaddition reaction under the influence of 1 mol% of dirhodium(II) tetrakis[N-benzene-fused-phthaloyl-(S)-piperidinonate], Rh(2)(S-BPTPI)(4), proceeded cleanly and gave, after treatment with acetyl chloride, the corresponding dihydropyranones in up to 99% ee.