Asymmetric tandem conjugate addition and reaction with carbocations on acylimidazole Michael acceptors

• Brigita Mudráková,
• Renata Marcia de Figueiredo,
• Jean-Marc Campagne and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 881–888, doi:10.3762/bjoc.19.65

• obtained by other conjugate addition reactions. Keywords: acylimidazole; asymmetric catalysis; carbocation; conjugate addition; enolate; Introduction Asymmetric metal-catalyzed conjugate additions provide access to numerous chiral scaffolds. This type of C–C bond formation efficiently enables the

• . Results and Discussion For initial experiments, we have selected the conjugate addition of Me2Zn to acylimidazole 1a catalyzed by a chiral NHC ligand derived from imidazolium salt L1. This NHC precursor has been described previously by Gérard, Mauduit, Campagne and co-workers [19]. The ligand L1 is

• acylimidazole 3a (Table 1, entry 5) as monitored by TLC analysis. The reaction was completed after 3 hours, meaning that the in situ-formed enolate needed 3.3 equiv of tropylium NTf2 (2a) to complete the reaction. By this route, the tandem product 3a was isolated in a high yield of 93% but without any

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• enantioselectivities. Aliphatic chains gave a high degree of enantioselectivity (up to 98%), while more moderate ees were noted when the substrates were branched at the γ-site (Scheme 70) [133]. The absolute configuration at each stereogenic center was determined by subsequent conversion of the borylated acylimidazole

Copper-catalyzed enantioselective conjugate addition of organometallic reagents to challenging Michael acceptors

• Delphine Pichon,
• Jennifer Morvan,
• Christophe Crévisy and
• Marc Mauduit

Beilstein J. Org. Chem. 2020, 16, 212–232, doi:10.3762/bjoc.16.24

• accomplished in this stimulating field. Keywords: acylimidazole; N-acyloxazolidinone; N-acylpyrrole; N-acylpyrrolidinone; aldehyde; amide; copper catalysis; electron-deficient alkenes; enantioselective conjugate addition; Michael acceptor; thioester; Introduction Generating high molecular complexity and

• , the acylimidazole moiety constituted a privileged surrogate of esters, amides, ketones, and aldehydes. Indeed, this peculiar function, which was readily accessible from the corresponding aldehydes or Weinreb amides, could be efficiently converted into a wide range of carbonyl derivatives, as depicted

• in Scheme 13. The successful use of α,β-unsaturated acylimidazole in Cu ECAs using organometallic reagents has been introduced very recently. Pioneering works in this field were published in 2011 by Roelfes, Liskamp, and co-workers, with the 1,4-addition of dimethyl malonate to cinnamyl 2-acyl-1

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• and his group developed an electrochemical strategy for the asymmetric alkylation of 2-acylimidazole derivatives 94 with substituted para-methylphenols 95 using Ni(OAc)2 as a Lewis acid catalyst in presence of chiral diamine ligand 96 (Scheme 34) [71]. Based on their detailed mechanistic studies, the

• to 2-acylimidazole derivatives 94 generates the Lewis acid/enolate complex 100 upon deprotonation (Scheme 35). This is followed by the formation of intermediate 101 by electrolysis-induced SET oxidation. In a parallel electrochemical cycle, benzylic radical species 95 was delivered by the anodic

Microwave-assisted synthesis of biologically relevant steroidal 17-exo-pyrazol-5'-ones from a norpregnene precursor by a side-chain elongation/heterocyclization sequence

• Gergő Mótyán,
• László Mérai,
• Márton Attila Kiss,
• Zsuzsanna Schelz,
• Izabella Sinka,
• István Zupkó and
• Éva Frank

Beilstein J. Org. Chem. 2018, 14, 2589–2596, doi:10.3762/bjoc.14.236

• -activated acylimidazole derivative was then converted to a β-ketoester containing a two carbon atom-elongated side chain than that of the starting material. A Knorr cyclization of the bifunctional 1,3-dicarbonyl compound with hydrazine and its monosubstituted derivatives in AcOH under microwave heating

1-n-Butyl-3-methylimidazolium-2-carboxylate: a versatile precatalyst for the ring-opening polymerization of ε-caprolactone and rac-lactide under solvent-free conditions

• Astrid Hoppe,
• Faten Sadaka,
• Claire-Hélène Brachais,
• Gilles Boni,
• Jean-Pierre Couvercelle and
• Laurent Plasseraud

Beilstein J. Org. Chem. 2013, 9, 647–654, doi:10.3762/bjoc.9.73

•  2). The protonation of the formed zwitterionic acylimidazole intermediate by the alcohol initiator followed by the attack of the thereby obtained alkoxide regenerates the carbene species. The chain propagation is by the attack of the newly formed hydroxy-terminated monomer (I) on another