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N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts.

ABSTRACT: The synthesis of bifunctional N-sulfinylureas and thioureas with an appended pyrrolidine unit is presented. These organocatalysts were evaluated in Michael additions of aldehydes to nitroalkenes both under solvent-free conditions and in solution. The N-sulfinylurea catalyst was more efficient than the corresponding thiourea. For some substrates, enantioselectivities reached 98% ee. The stereogenic center on the sulfur did not have a considerable influence on the catalytic reactions. Under ball-milling conditions, the Michael adducts were obtained in good yields but with slightly lower enantiomeric purities than in solution. DFT calculations elucidated its mode of action and confirmed a dual activation mode, which combines enamine activation of aldehydes and hydrogen-bond activation of nitroalkenes.

SUBMITTER: Polackova V

PROVIDER: S-EPMC8561142 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts.

Poláčková Viera V Krištofíková Dominika D Némethová Boglárka B Górová Renata R Mečiarová Mária M Šebesta Radovan R

Beilstein journal of organic chemistry 20211025

The synthesis of bifunctional N-sulfinylureas and thioureas with an appended pyrrolidine unit is presented. These organocatalysts were evaluated in Michael additions of aldehydes to nitroalkenes both under solvent-free conditions and in solution. The N-sulfinylurea catalyst was more efficient than the corresponding thiourea. For some substrates, enantioselectivities reached 98% ee. The stereogenic center on the sulfur did not have a considerable influence on the catalytic reactions ...[more]

PMID: 34795800

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