Stereoselective mechanochemical synthesis of thiomalonate Michael adducts via iminium catalysis by chiral primary amines

• Michał Błauciak,
• Dominika Andrzejczyk,
• Błażej Dziuk and
• Rafał Kowalczyk

Beilstein J. Org. Chem. 2024, 20, 2313–2322, doi:10.3762/bjoc.20.198

• hour compared to 24 or even 168 hours in solution-based reactions. It is noteworthy that this represents one of the early reports on the application of iminium catalysis using first-generation chiral amines under mechanochemical conditions, along with the utilization of easily enolizable thioesters as

• nucleophiles in this transformation. Keywords: asymmetric catalysis; iminium catalysis; mechanochemistry; organocatalysis; thioesters; Introduction Mechanochemistry, particularly solventless processes under ball milling conditions, offers the opportunity to devise unconventional reaction pathways [1][2][3][4

• novel approach based on iminium catalysis employing chiral primary amines under ball milling conditions. Ball milling induces localized and transient temperature and pressure increases which could influence changes in the free activation volume [32][33][34], favoring Michael additions [35]. Furthermore

Primary amine-catalyzed enantioselective 1,4-Michael addition reaction of pyrazolin-5-ones to α,β-unsaturated ketones

• Pooja Goyal,
• Akhil K. Dubey,
• Raghunath Chowdhury and
• Amey Wadawale

Beilstein J. Org. Chem. 2024, 20, 1518–1526, doi:10.3762/bjoc.20.136

• yields (up to 97%) and high enantioselectivities (up to 98.5% ee) under mild reaction conditions. In addition, this protocol was further expanded to synthesize highly enantioenriched hybrid molecules bearing biologically relevant heterocycles. Keywords: α,β-unsaturated ketones; iminium catalysis

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

• published by Zou and Bach [12], so the following are selected examples and recent developments of the field. Amine catalysis can be broadly split into enamine and iminium catalysis, both of which have been utilised in combination with photocatalysis. The first example of enamine catalysis in combination

Synergistic chiral iminium and palladium catalysis: Highly regio- and enantioselective [3 + 2] annulation reaction of 2-vinylcyclopropanes with enals

• Haipan Zhu,
• Peile Du,
• Jianjun Li,
• Ziyang Liao,
• Guohua Liu,
• Hao Li and
• Wei Wang

Beilstein J. Org. Chem. 2016, 12, 1340–1347, doi:10.3762/bjoc.12.127

• Chemistry, Shanghai Normal University, Shanghai 200234, China Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131-0001, USA 10.3762/bjoc.12.127 Abstract A cooperative catalytic strategy of chiral iminium catalysis by regioselective activation of the C=C bond in

• Lewis acid (LA) catalysis strategy (Scheme 1, reaction 2) [49][50][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76]. The iminium catalysis plays an important dual role in the process. The formed iminium ion 4 derived from aldehyde 1 and an amine catalyst activates the C=C

(Thio)urea-mediated synthesis of functionalized six-membered rings with multiple chiral centers

• Giorgos Koutoulogenis,
• Nikolaos Kaplaneris and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2016, 12, 462–495, doi:10.3762/bjoc.12.48

• results of this reaction were excellent with a 54% yield, 3.1:1:1 dr and >99% ee. The proposed mechanism, begins with an activation of the malonate 222 and the nitro-alkene 82, so a stereoselective Michael addition occurs. Thus, the formed adduct, through an iminium catalysis pathway caused by catalyst