1202701-99-2Relevant academic research and scientific papers
Stereoselective Functionalization of Racemic Cyclopropylzinc Reagents via Enantiodivergent Relay Coupling
An, Lun,Tong, Fei-Fei,Zhang, Shu,Zhang, Xingang
supporting information, p. 11884 - 11892 (2020/08/06)
Efficient construction of optically pure molecules from readily available starting materials in a simple manner is an ongoing goal in asymmetric synthesis. As a straightforward route, transition-metal-catalyzed enantioconvergent coupling between widely available secondary alkyl electrophiles and organometallic nucleophiles has emerged as a powerful strategy to construct chiral center(s). However, the scope of racemic secondary alkylmetallic nucleophiles for this coupling remains limited in specific substrates because of the difficulties in stereoselective formation of the key alkylmetal intermediates. Here, we report an enantiodivergent strategy to efficiently achieve an array of synthetically useful chiral cyclopropanes, including chiral fluoroalkylated cyclopropanes and enantiomerically enriched cyclopropanes with chiral side chains, from racemic cyclopropylzinc reagents. This strategy relies on a one-pot, two-step enantiodivergent relay coupling process of the racemic cis-cyclopropylzinc reagents with two different electrophiles, which involves kinetic resolution of racemic cis-cyclopropylzinc reagents through a nickel-catalyzed enantioselective coupling with alkyl electrophiles, followed by a stereospecific relay coupling of the remaining enantiomeric cyclopropylzinc reagent with various electrophiles, to produce two types of functionalized chiral cyclopropanes with opposite configurations on the cyclopropane ring. These chiral cyclopropanes are versatile synthons for diverse transformations, rendering this strategy effective for obtaining structurally diversified molecules of medicinal interest.
Highly enantioselective synthesis of 1,2,3-substituted cyclopropanes by using α-iodo- and α-chloromethylzinc carbenoids
Beaulieu, Louis-Philippe B.,Zimmer, Lucie E.,Gagnon, Alexandre,Charette, André B.
supporting information, p. 14784 - 14791 (2013/01/15)
Herein, we report the enantio- and diastereoselective formation of trans-iodo- and trans-chlorocyclopropanes from α-iodo- and α-chlorozinc carbenoids by using a dioxaborolane-derived chiral ligand. The synthetically useful iodocyclopropane building blocks were derivatized by an electrophilic trapping of the corresponding cyclopropyl lithium species or a Negishi coupling to give access to a variety of enantioenriched 1,2,3-substituted cyclopropanes. The synthetic utility of this method was demonstrated by the formal synthesis of an HIV-1 protease inhibitor. In addition, the related stereoselective bromocyclopropanation was also investigated. New insights about the relative electrophilicity of haloiodomethylzinc carbenoids are also presented. Propping up the enantioselectivity: The enantio- and diastereoselective formation of trans-iodo- and trans-chlorocyclopropanes from α-iodo- and α-chlorozinc carbenoids by using a dioxaborolane-derived chiral ligand is reported. The iodocyclopropanes were derivatized into a variety of 1,2,3-substituted cyclopropanes and new insights into the relative electrophilicity of α-haloiodomethylzinc carbenoids are presented (see scheme). Copyright
Enantio-and diastereoselective iodocyclopropanation of allylic alcohols by using a substituted zinc carbenoid
Beaulieu, Louis-Philippe B.,Zimmer, Lucie E.,Charette, Andr B.
supporting information; experimental part, p. 11829 - 11832 (2010/06/15)
The first enantioselective Simmons Smith iodocyclopropanation reaction, in which iodoform is used as the precursor to the substituted zinc carbenoid, was reported. The nature of the carbenoid was examined by quenching the preformed zinc carbenoid with Ds
