Asymmetric cycloaddition of anthrone with N-substituted maleimides with C-2-chiral pyrrolidines

Base-catalyzed asymmetric cycloaddition of anthrone with achiral and chiral N-substituted maleimides was carried out in the presence of C-2-chiral pyrrolidines in almost quantitative yields. Chiral, non-racemic [4+2] adducts up to 61% ee were produced with achiral N-methyl and N-benzylmaleimide using the chiral catalysts. De's of the adducts up to 38% were observed in the cases of chiral N-substituted maleimides and achiral pyrrolidine, in which the absolute configuration of the major product was established by X-ray analysis. The combination of chiral maleimides and chiral catalysts afforded the adducts having up to 80% de. (C) 1997 Published by Elsevier Science Ltd. All rights reserved.