Zinc, Lithium and Magnesium Carbenoids: Chemical Properties and Relevant Applications in Organic Synthesis

Nishimura, Rodolfo Hideki Vicente; Murie, Valter E.; Soldi, Rafael A.; Lopes, João Luís Callegari; Clososki, Giuliano C.

doi:10.5935/0103-5053.20150218

Cited by 7 publications

(4 citation statements)

References 1 publication

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“…Both diastereoisomers at the benzylic carbon center (C 1 ) give the same ( Z )-silyl enol ether 41 , suggesting that the stereochemistry of the α-hydroxysilane (C 1 ) is irrelevant to the stereochemistry of the formed double bond. The in situ-formed magnesiate carbenoid is therefore configurationally unstable and rapidly equilibrates , into the most stable diastereoisomer before ring fragmentation (Scheme , path b). On the other hand, when 39 is treated with a less reactive dialkylmagnesium (Scheme , path c) or even a Grignard reagent (Scheme , path a), the Brook rearrangement occurs, but the intermediate is not nucleophilic enough to promote the ring opening and therefore decomposes into carbene 43 . − When the carbene is formed from the deprotonation reaction with the Grignard reagent (Scheme , path a), with concomitant formation of Me 3 SiOMgBr, 43 undergoes a ring expansion to provide polysubstituted cyclobutene 40 as a single diastereomers.…”

Section: Metal-mediated Ring Cleavagementioning

confidence: 99%

Creating Stereocenters within Acyclic Systems by C–C Bond Cleavage of Cyclopropanes

2020

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Recent developments in the stereoselective synthesis of polysubstituted cyclopropanes nowadays allow chemists to easily access these strained rings with high diastereo-and enantiomeric ratios. In turn, this development has created a paradigm shift for the synthesis of stereodefined acyclic molecules though selective carbon−carbon bond cleavage. Through chosen illustrative examples, we aim to show in this review that the cleavage of cyclopropane is a powerful approach to reveal sp 3 stereocenters in acyclic systems. The application of these concepts was illustrated by the total syntheses of several natural products and other important molecules, further showing the power of these strategies as a powerful tool in organic synthesis.

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Section: Metal-mediated Ring Cleavagementioning

confidence: 99%

Creating Stereocenters within Acyclic Systems by C–C Bond Cleavage of Cyclopropanes

2020

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“…Chloro-substituted quinolines are important intermediates in medicinal chemistry . For instance, 4,7-dichloroquinoline is a valuable precursor to the antimalarial chloroquine. , Given our interest in developing selective strategies to functionalize aromatic and heteroaromatic substrates, − we recently sort to prepare some novel di- and tri-functionalized quinolines by using regioselective metalation strategies . Herein, we report the preparation of a library of functional quinolines through the fast and efficient magnesiation of halogenated substrates under mild conditions.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of 7-Chloroquinoline Derivatives Using Mixed Lithium-Magnesium Reagents

et al. 2021

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We have prepared a library of functionalized quinolines through the magnesiation of 7-chloroquinolines under mild conditions, employing both batch and continuous flow conditions. The preparation involved the generation of mixed lithium-magnesium intermediates, which were reacted with different electrophiles. Mixed lithium-zinc reagents allowed the synthesis of halogenated and arylated derivatives. Some of the synthesized 4-carbinol quinolines have shown interesting antiproliferative properties, their hydroxyl group being a suitable amino group bioisostere. We also report a two-step approach for optically active derivatives.

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“…Thus, we depict here the differentiated reactivities of vinyl carbene derived from cyclopropene with zinc or rhodium complexes as promoters (Figure 1C). For the zinc halide-promoted reaction, the generated ambiphilic zinc carbenoid (Pasco et al., 2013, Nishimura et al., 2015), which is the key intermediate in the Simmons-Smith (SS) reaction (Denmark et al., 1991, Denmark et al., 1992), shows a nucleophilic character and undergoes nucleophilic attack to isatins without elimination of the halogen atom, delivering oxindole derivatives 3 containing a synthetically valuable alkenyl halide moiety. Importantly, despite the theoretical nucleophilicity, the nucleophilic reactivity of the zinc carbenoid without elimination of halogen atoms has never been achieved (Knochel et al., 1989, Retherford et al., 1989), which provides unique access to alkenyl halides using inexpensive and non-toxic zinc halides as halogenating agents under very mild conditions.…”

Section: Introductionmentioning

confidence: 99%

Metal-Dependent Umpolung Reactivity of Carbenes Derived from Cyclopropenes

2019

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Summary Metal carbenes, divalent carbon species, are versatile intermediates that enable novel synthetic pathways. These species exhibit either electrophilic or nucleophilic character, depending on the carbene and metal fragments. Although the metal carbene reactivity is regulated by the metal, the umpolung of carbene reactivity by changing metal remains challenging. Here, we report a unique metal-induced de novo umpolung of carbene reactivity, wherein a carbene precursor can be transformed into either an electrophilic carbene or a nucleophilic carbenoid, depending on the metal promoters. Thus, a chemodivergent reaction of isatins and cyclopropenes is developed. Under the promotion of Zn 2+ halides, a nucleophilic zinc carbenoid is formed and trapped by isatins to produce oxindole derivatives containing an alkenyl halide moiety. Using Rh 2 (esp) 2 as a catalyst, the reaction delivers oxindoles carrying a dihydrofuran unit. This work provides a facile approach to harness the metal carbene reactivity and is critical for the development of diversity-oriented synthesis.

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Zinc, Lithium and Magnesium Carbenoids: Chemical Properties and Relevant Applications in Organic Synthesis

Cited by 7 publications

References 1 publication

Creating Stereocenters within Acyclic Systems by C–C Bond Cleavage of Cyclopropanes

Creating Stereocenters within Acyclic Systems by C–C Bond Cleavage of Cyclopropanes

Synthesis of 7-Chloroquinoline Derivatives Using Mixed Lithium-Magnesium Reagents

Metal-Dependent Umpolung Reactivity of Carbenes Derived from Cyclopropenes

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