Asymmetric cycloaddition of anthrone with N-substituted maleimides with C2-chiral pyrrolidines
摘要:
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.
Mn(I)-Catalyzed Preferential Electrophilic C3-Maleimidation in Quinoxaline Leading to Spirocyclization and Dehydrogenation of Succinimides
作者:Subhendu Ghosh、Tamanna Khandelia、Pritishree Panigrahi、Raju Mandal、Bhisma K. Patel
DOI:10.1021/acs.orglett.3c01350
日期:2023.5.26
A Mn(I)-catalyzed site-selective nondirected C3-maleimidation of quinoxaline is established. Herein, the electrophilic C3-metalation precedes over the o-directed strategy to access diversely substituted quinoxaline-appended succinimides. The products undergo PIFA-promoted C(sp2)–C(sp3) spirocyclization via π-electrons drifting from aryls and Selectfluor-mediated dehydrogenation of succinimide at room