Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

• [27]. This transformation led to a series of axially chiral cycl[3.2.2]azines 24 in good yields and high enantiomeric purities (Scheme 8). The proposed mechanism comprises enamine activation, condensation with nitroolefin 23, ring closure, and catalyst elimination to provide the axially chiral product

Evaluation of the enantioselectivity of new chiral ligands based on imidazolidin-4-one derivatives

• Jan Bartáček,
• Karel Chlumský,
• Jan Mrkvička,
• Lucie Paloušová,
• Miloš Sedlák and
• Pavel Drabina

Beilstein J. Org. Chem. 2024, 20, 684–691, doi:10.3762/bjoc.20.62

• chiral metal complex catalyst but also as an enantioselective organocatalyst [17]. Accordingly, its application in enantioselective organocatalysis, particularly in asymmetric reactions through “enamine activation”, warrants further investigation. Results and Discussion The corresponding copper(II

• -tetrazole, which was successfully used in many asymmetric reactions via “enamine activation”, especially in asymmetric aldol reactions [20][21][22][23]. Moreover, compound IV was previously included in a study dealing with asymmetric cascade reactions (based on aldol reactions) of aldehydes with α-keto

N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts

• Viera Poláčková,
• Dominika Krištofíková,
• Boglárka Némethová,
• Renata Górová,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2021, 17, 2629–2641, doi:10.3762/bjoc.17.176

• 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

• unit, which should engage in enamine activation of enolizable carbonyl compounds. The urea or thiourea moiety shall provide hydrogen-bond donating ability. Furthermore, these compounds possess a sulfinyl group with an additional stereogenic center on the sulfur. To verify the influence of a matched

• bifunctional pyrrolidine-containing sulfinylureas and thioureas. These catalysts operate via enamine activation of aldehydes and hydrogen-bond activation of the electrophilic component, in this study – nitrostyrenes. These catalysts were effective in the Michael addition of aldehydes to nitroalkenes, affording

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

• Jan Wallbaum and
• Daniel B. Werz

Beilstein J. Org. Chem. 2017, 13, 2577–2583, doi:10.3762/bjoc.13.254

• ; MacMillan catalyst; organocatalysis; Introduction Organocatalytic iminium and enamine activation has attracted organic chemists for more than one century [1]. Until today a wide and constantly increasing number of different organocatalytic transformations with various substrates have been accomplished [2

(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

• efficient ways of constructing six-membered rings. Activation of carbonyl compounds via enamine and iminium intermediates [2]. Electronic and steric interactions present in enamine activation mode [2]. Electrophilic activation of carbonyl compounds by a thiourea moiety. Asymmetric synthesis of dihydro-2H

Primary-tertiary diamine-catalyzed Michael addition of ketones to isatylidenemalononitrile derivatives

• Akshay Kumar and
• Swapandeep Singh Chimni

Beilstein J. Org. Chem. 2014, 10, 929–935, doi:10.3762/bjoc.10.91

• -tertiary diamine organocatalysts for Michael reaction via enamine activation has not been investigated so far [38]. With readily available and inexpensive natural amino acids as a chiral source, we developed very simple primary-tertiary diamine organocatalysts (Figure 2) for asymmetric aldol reactions [44

Secondary amine-initiated three-component synthesis of 3,4-dihydropyrimidinones and thiones involving alkynes, aldehydes and thiourea/urea

• Jie-Ping Wan,
• Yunfang Lin,
• Kaikai Hu and
• Yunyun Liu

Beilstein J. Org. Chem. 2014, 10, 287–292, doi:10.3762/bjoc.10.25

• ; enamine activation; multicomponent reactions; Introduction DHPMs are well-known heterocyclic scaffolds with abundant biological relevance [1][2][3]. The DHPM backbone has been found in a class of marine natural products possessing anti-HIV activity [4]. What’s more, diversified other biological

Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach

• Pankaj Chauhan and
• Swapandeep Singh Chimni

Beilstein J. Org. Chem. 2012, 8, 2132–2141, doi:10.3762/bjoc.8.240

• various bioactive molecules [28]. Among different organocatalysts used for asymmetric aldol reactions, proline and its derivatives emerged as powerful catalysts for the enamine activation of donor aldehyde or ketone. Bolm’s group reported a solvent-free asymmetric organocatalytic aldol reaction under ball

Organocatalytic tandem Michael addition reactions: A powerful access to the enantioselective synthesis of functionalized chromenes, thiochromenes and 1,2-dihydroquinolines

• Chittaranjan Bhanja,
• Satyaban Jena,
• Sabita Nayak and
• Seetaram Mohapatra

Beilstein J. Org. Chem. 2012, 8, 1668–1694, doi:10.3762/bjoc.8.191

• the literature up to 2011. Keeping an overview of organocatalytic modes of activation, and taking the less reactive Michael acceptor into account, we discuss here only the iminium/enamine activation or dual activation by iminium and hydrogen-bonding interaction strategies followed by cyclization, for

• -benzothiopyrans 37 using the closely related catalyst Ia through the same iminium-enamine activation mode of the α,β-unsaturated aldehydes 2. The asymmetric domino reactions proceeded with high yields (53–93%) and with excellent chemo- and stereoselectivities (up to 98% ee) in chloroform as solvent (Scheme 19

A quantitative approach to nucleophilic organocatalysis

• Herbert Mayr,
• Sami Lakhdar,
• Biplab Maji and
• Armin R. Ofial

Beilstein J. Org. Chem. 2012, 8, 1458–1478, doi:10.3762/bjoc.8.166

• -imidazoline relative to 2-benzylidene-imidazolidine is explained by the gain of aromaticity during electrophilic additions to the imidazoline derivatives. O-Methylated Breslow intermediates are a hundred-fold less nucleophilic than deoxy Breslow intermediates. Keywords: enamine activation; iminium activation

• constants [64]. Electrostatic activation of iminium activated cyclopropanations with sulfur ylides. Sulfur ylides inhibit the formation of iminium ions. Enamine activation [65]. Electrophilicity parameters E for classes of compounds that have been used as electrophilic substrates in enamine activated

Asymmetric organocatalytic decarboxylative Mannich reaction using β-keto acids: A new protocol for the synthesis of chiral β-amino ketones

• Chunhui Jiang,
• Fangrui Zhong and
• Yixin Lu

Beilstein J. Org. Chem. 2012, 8, 1279–1283, doi:10.3762/bjoc.8.144

• great practical value. Indeed, direct approaches such as asymmetric enamine catalysis [14][15][16][17] and Brønsted acid catalysis [18] have been reported, through the activation of ketones or aryl imines [19]. However, substrates for the enamine activation are limited to only acetone and cyclic alkyl