Facile Access to Cyclopropylboronates via Stereospecific Deborylative Cyclization: A Leaving Group‐Assisted Activation of Geminal Diborons

Chen, Xinyi; Gao, Feng-Chen; Ning, Peng-Fei; Wei, Yi; Hong, Kai

doi:10.1002/anie.202302638

Cited by 16 publications

(6 citation statements)

References 118 publications

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“…This protocol also exhibited high tolerance to functional groups such as alkenes, nitrile, ester, and bromo groups (20)(21)(22)(23)(24)(25). Moreover, naphthalene, a wide variety of aromatic heterocycles, and complex frameworks derived from drug molecules were all found to be suitable components (26)(27)(28)(29)(30)(31)(32)(33)(34)(35), showing the potential for late-stage functionalization. In some cases, a lower initial temperature was adopted to minimize the background reactions between the Grignard reagents and the sensitive functional groups.…”

Section: Resultsmentioning

confidence: 97%

“…Following Aggarwal's protocol, [25] one of the B(pin) groups in 46 could undergo a transition metal-free C(sp 2 )À C(sp 3 ) coupling to afford tertiary boronate 95 in moderate yield. Treatment of 42 with photoinduced bromination followed by deborylative cyclization [26] afforded cyclopropylboronate 96 in a diastereoselective manner. Furthermore, with the activation of a Lewis base, 14 could also engage with quinoline-N-oxide [4i,27] and ester/NFSI [4p] to generate 97 and 98, respectively.…”

Section: Methodsmentioning

confidence: 99%

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A General Method to Access Sterically Encumbered Geminal Bis(boronates) via Formal Umpolung Transformation of Terminal Diboron Compounds

Ning,

Wei,

Chen

et al. 2023

Angew Chem Int Ed

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General methods for the preparation of geminal bis(boronates) are of great interest due to their widespread applications in organic synthesis. While the terminal gem‐diboron compounds are readily accessible, the construction of the sterically encumbered, internal analogues has remained a prominent challenge. Herein, we report a formal umpolung strategy to access these valuable building blocks. The readily available 1,1‐diborylalkanes were first converted into the corresponding α‐halogenated derivatives, which then serve as electrophilic components, undergoing a formal substitution with a diverse array of nucleophiles to form a series of C−C, C−O, C−S, and C−N bonds. This protocol features good tolerance to steric hindrance and a wide variety of functional groups and heterocycles. Notably, this strategy can also be extended to the synthesis of diaryl and terminal gem‐diboron compounds, therefore providing a general approach to various types of geminal bis(boronates).

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Section: Resultsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

A General Method to Access Sterically Encumbered Geminal Bis(boronates) via Formal Umpolung Transformation of Terminal Diboron Compounds

Ning,

Wei,

Chen

et al. 2023

Angew Chem Int Ed

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“…The cyclopropanation reaction enabled by the 1,3relationship between the iodomethyl and boronic ester functionalities [9,59] should provide an access to fused bicyclic cyclopropylboronic acid derivatives. [11,[60][61][62][63] Cyclopropylboronates are valuable building blocks allowing for a wide range of transformations such as conversion to cyclopropanols [64,65] and cyclopropylamines, [64,66] CÀ C bond formation using Matteson [67][68][69] and Zweifel [64] as well as Suzuki-Miyaura [70,71] cross-coupling reactions. [65][66][67][68][69][70][71][72][73] Recently, we briefly explored the formation of bicyclo[3.1.0]hexanes from ATRAn product (Scheme 1, A).…”

Section: Preparation Of Fused Cyclopropanesmentioning

confidence: 99%

Access to γ‐Iodo‐gem‐Diborylated Cyclopentanes and to Bicyclic Cyclopropanes

Circule,

Dénès,

Renaud

2024

Adv Synth Catal

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A formal atom transfer radical [3+2] annulation (ATRAn) reaction between different homoallyl radical precursors and 1,1‐diborylethene was developed. It provides a rapid access to polysubstituted cyclopentanes containing a gem‐diboronic ester moiety. The synthetic utility of theses uniquely functionalized 5‐membered rings is highlighted by their easy conversion to attractive borylated building blocks such as 1‐borylated bicyclo[3.1.0]hexanes. The ATRAn reaction was extended to homopropagylic radicals giving access to unique allylic gem‐diboronic esters that could be used in allylboration of aldehydes. Furthermore, this work highlights that 1,1‐diborylethene represents a synthetic equivalent to ketene, a so far elusive radical trap due to its daunting reactivity.

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“…Recently, the Hong and Cho groups independently synthesized enantioenriched cyclopropylboronates via a two-step three-component reaction of chiral epoxides with lithiated gem -diboronates and diphenyl chlorophosphate (Fig. 1a 3 ) 31 , 32 . Noyori realized the only example of an oxygen-carbon exchange reaction by heating with ethyl diazoacetate at 130–140 °C, where small amounts of competing C–O and C–H insertion products were also formed (Fig.…”

Section: Introductionmentioning

confidence: 99%

Silver-catalyzed direct conversion of epoxides into cyclopropanes using N-triftosylhydrazones

Li,

Sivaguru,

Wei

et al. 2024

Nat Commun

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Epoxides, as a prominent small ring O-heterocyclic and the privileged pharmacophores for medicinal chemistry, have recently represented an ideal substrate for the development of single-atom replacements. The previous O-to-C replacement strategy for epoxides to date typically requires high temperatures to achieve low yields and lacks substrate range and functional group tolerance, so achieving this oxygen-carbon exchange remains a formidable challenge. Here, we report a silver-catalyzed direct conversion of epoxides into trifluoromethylcyclopropanes in a single step using trifluoromethyl N-triftosylhydrazones as carbene precursors, thereby achieving oxygen-carbon exchange via a tandem deoxygenation/[2 + 1] cycloaddition. The reaction shows broad tolerance of functional groups, allowing routine cheletropic olefin synthesis in a strategy for the net oxygen-carbon exchange reaction. The utility of this method is further showcased with the late-stage diversification of epoxides derived from bioactive natural products and drugs. Mechanistic experiments and DFT calculations elucidate the reaction mechanism and the origin of the chemo- and stereoselectivity.

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Facile Access to Cyclopropylboronates via Stereospecific Deborylative Cyclization: A Leaving Group‐Assisted Activation of Geminal Diborons

Cited by 16 publications

References 118 publications

A General Method to Access Sterically Encumbered Geminal Bis(boronates) via Formal Umpolung Transformation of Terminal Diboron Compounds

A General Method to Access Sterically Encumbered Geminal Bis(boronates) via Formal Umpolung Transformation of Terminal Diboron Compounds

Access to γ‐Iodo‐gem‐Diborylated Cyclopentanes and to Bicyclic Cyclopropanes

Silver-catalyzed direct conversion of epoxides into cyclopropanes using N-triftosylhydrazones

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