Synthesis of 1,3-cis-disubstituted sterically encumbered imidazolidinone organocatalysts

Abstract

A variety of novel imidazolidinone-based organocatalysts with bulky substituents were synthesized under mild reaction conditions starting from easily accessible substrates. Different natural and unnatural amino acid methyl amides were cyclized with aromatic carbaldehydes to yield two diastereomeric MacMillan-type catalysts. Special emphasis was put on bulky residues such as mesityl and pyrene moieties.

Exploiting Heavier Organochalcogen Compounds in Donor–Acceptor Cyclopropane Chemistry

“…22 Inspired by these results and by another work from Sparr and Gilmour leading to an asymmetric ring-opening 1,3-bischlorination, 23 we envisioned an enantioselective desymmetrization reaction of achiral meso-cyclopropyl carbaldehydes 16 with sulfenyl and selenyl chlorides 17 by employing chiral imidazolidinone organocatalysts. 24 Based on the highly polarized S/Se−Cl bond, we proposed that chloride could act as the nucleophilic source, whereas the positively polarized chalcogen would act as the electrophilic counterpart. The aldehyde-functionalized cyclopropanes underwent smoothly the anticipated reaction, leading to 1,3-halochalcogenated products 18 with complete regioselectivity.…”