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

• min. Subsequently, 1.2 M dimethylzinc reagent in toluene (0.31 mL, 0.38 mmol, 1.5 equiv) was added dropwise to the solution and the resulting mixture was also stirred for 10 min. The acylimidazole (0.25 mmol, 1.0 equiv) dissolved in anhydrous THF (0.5 mL) was added dropwise to the mixture. The

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

• -product, some Grignard or aluminium reagents remain too reactive and incompatible with some electron-withdrawing functions. In contrast, some organometallic reagents, such as dimethylzinc, are poorly reactive and require a higher electrophilicity of the Michael acceptors to provide the desired conjugated

• variety of cyclic and acyclic aldehydes 1. High 1,4-regioselectivities and promising stereoselectivities ranging from 27 to 90% ee were achieved (Scheme 2a). It is noteworthy that the addition of dimethylzinc was also successfully achieved, as the desired 1,4-methylated products were exclusively formed in

• -substitution of enals [21]. By using (R)-BINAP (L2)/CuTC in combination with chiral prolinol derivatives L4–6 as organocatalysts, various α,β-functionalized aldehydes were synthesized in good isolated yields (57–74%) and remarkable enantioselectivity (99%) from diethylzinc or dimethylzinc as nucleophiles and

Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes

• Ruben Pomar Fuentespina,
• José Angel Garcia de la Cruz,
• Gabriel Durin,
• Victor Mamane,
• Jean-Marc Weibel and
• Patrick Pale

Beilstein J. Org. Chem. 2019, 15, 1416–1424, doi:10.3762/bjoc.15.141

• . Utimoto’s group was probably the first who reported on the treatment of oxiranyllithium with diethylzinc or trimethylaluminium [5]. Shimizu et al. demonstrated that in situ formed trifluoromethyloxiranyllithium derivatives reacted with trimethylaluminium, dimethylzinc or organoboranes to yield

One-pot activation–alkynylation–cyclization synthesis of 1,5-diacyl-5-hydroxypyrazolines in a consecutive three-component fashion

• Christina Görgen,
• Katharina Boden,
• Guido J. Reiss,
• Walter Frank and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 1360–1370, doi:10.3762/bjoc.15.136

• (Figure 2) [26][27]. In addition, 1-acyl-5-hydroxypyrazolines are bidentate ligands for zinc complexes and by virtue of being ring tautomers of β-enolhydrazones they can also act as tridentate ligands for nickel [28] and tin [29][30] complexes. In contrast, dimethylzinc forms dimeric complexes where the 1

Copper-catalyzed asymmetric methylation of fluoroalkylated pyruvates with dimethylzinc

• Kohsuke Aikawa,
• Kohei Yabuuchi,
• Kota Torii and
• Koichi Mikami

Beilstein J. Org. Chem. 2018, 14, 576–582, doi:10.3762/bjoc.14.44

• fluoroalkylated pyruvates is shown with dimethylzinc as a methylating reagent in the presence of a copper catalyst bearing a chiral phosphine ligand. This is the first catalytic asymmetric methylation to synthesize various α-fluoroalkylated tertiary alcohols with CF3, CF2H, CF2Br, and n-CnF2n+1 (n = 2, 3, 8

• copper. Keywords: asymmetric methylation; chiral phosphine ligand; copper catalyst; dimethylzinc; trifluoropyruvate; Introduction The introduction of fluorine atoms into organic compounds plays an important role in the discovery of lead candidates with unique biological and physicochemical properties

• . Herein, we disclose the catalytic asymmetric methylation of trifluoropyruvate derivatives as electrophiles and dimethylzinc as a methylating nucleophile by a chiral copper catalyst. This method is also applicable to the asymmetric synthesis of various α-fluoroalkylated tertiary alcohols bearing CF2H

Recent progress in the racemic and enantioselective synthesis of monofluoroalkene-based dipeptide isosteres

• Myriam Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2017, 13, 2637–2658, doi:10.3762/bjoc.13.262

• O-deprotection, N-Fmoc-protection and oxidation to the carboxylic acid afforded the final Fmoc-Ala-ψ[(Z)-CF=CH]-Gly (49). Then, it was discovered that the diastereoselectivity of the addition of the Grignard reagent on 47 was enhanced when dimethylzinc (Me2Zn) was used as an additive (Table 1) [39

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Copper-catalyzed asymmetric conjugate addition of organometallic reagents to extended Michael acceptors

• Thibault E. Schmid,
• Sammy Drissi-Amraoui,
• Christophe Crévisy,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2015, 11, 2418–2434, doi:10.3762/bjoc.11.263

• . Copper-catalyzed conjugate addition of trimethylaluminium onto nitro dienoates. Copper-catalyzed selective 1,4-ACA in total synthesis of erogorgiaene. 1,4-selective addition of diethylzinc onto a cyclic enynone catalyzed by a chiral NHC-based system. Cu-NHC-catalyzed 1,6-ACA of dimethylzinc onto an α,β,γ

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

• Kei Murakami and
• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 278–302, doi:10.3762/bjoc.9.34

• al. improved their copper-catalyzed carbometalation reactions of cyclopropenes by using functional-group-tolerable organozinc reagents (Scheme 22) such as dimethyl-, diethyl-, diphenyl-, diisopropyl-, and divinylzinc reagents [91]. Treatment of cyclopropene 3d with dimethylzinc in the presence of a

Radical zinc-atom-transfer-based carbozincation of haloalkynes with dialkylzincs

• Fabrice Chemla,
• Florian Dulong,
• Franck Ferreira and
• Alejandro Pérez-Luna

Beilstein J. Org. Chem. 2013, 9, 236–245, doi:10.3762/bjoc.9.28

• 1,4-addition/carbozincation of dialkylzincs or alkyl iodides based on zinc atom radical transfer, in the presence of dimethylzinc with β-(propargyloxy)enoates having pendant iodo- and bromoalkynes, is disclosed. Formation of the carbenoid intermediate is fully stereoselective at −30 °C and arises from

• following hydrolysis, is that (E)-4, formed from (E)-15 by H-abstraction, is present from the start. We finally considered the prospect to carry out the carbozincation of bromoalkynes using a combination of an alkyl iodide and dimethylzinc (Table 3). Towards this end, we first treated enoate 3a with Me2Zn

• shown that β-(propargyloxy)enoates having pendant iodo- and bromoalkynes undergo a 1,4-addition/carbozincation sequence by reaction with dialkylzincs or with alkyliodides in the presence of dimethylzinc. The sequence involves a radical chain mechanism initiated by air and provides the proof of concept

Homoallylic amines by reductive inter- and intramolecular coupling of allenes and nitriles

• Peter Wipf and
• Marija D. Manojlovic

Beilstein J. Org. Chem. 2011, 7, 824–830, doi:10.3762/bjoc.7.94

• Peter Wipf Marija D. Manojlovic Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, PA 15260, USA 10.3762/bjoc.7.94 Abstract The one-pot hydrozirconation of allenes and nitriles followed by an in situ transmetalation of the allylzirconocene with dimethylzinc or zinc

• intermolecular reaction using dimethylzinc in toluene for the transmetalation step. These new experiments produced results similar to the reactions in the presence of zinc chloride (Table 2). Next, we investigated the scope of the intramolecular reaction (Table 4). Both tetrahydrofuran and tetrahydropyran

• dimethylzinc, both (E)- and (Z)-allylzinc species can exist in the solution. The chelation of the zirconocene to the ether oxygen and the imine nitrogen leads to a preference for the (Z)-TS species, paving the way for the formation of the observed cis-product. To further elaborate on the utility of this