The coupling of alkylboronic acids and esters with Baylis–Hillman derivatives by Lewis base/photoredox dual catalysis

Ye, Hongqiang; Zhao, He; Ren, Shujian; Ye, Hongfeng; Cheng, Dongping; Li, Xiaonian; Xu, Xinhua

doi:10.1016/j.tetlet.2019.04.015

Cited by 30 publications

(15 citation statements)

References 46 publications

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“…In 2019, Xu and co‐workers utilized the same activation strategy to couple alkyl boronic acids or esters with Baylis‐Hillman derivatives, generating α , β ‐unsaturated carbonyl compounds (Scheme 6). [29] As highlighted in their report, the synthesis of trisubstituted alkenes remains highly dependent on the use of harsh conditions. Nevertheless, employing DABCO as the activating Lewis base, they were able to form the desired products in good to moderate yield.…”

Section: Radical Generation Through a Reductive Quenching Cyclementioning

confidence: 99%

Uncovering the Potential of Boronic Acid and Derivatives as Radical Source in Photo(electro)chemical Reactions

et al. 2022

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The chemistry of boron compounds has been profoundly investigated in the last decades, leading to ubiquity in many synthetic applications as well as biologically active molecules. Since the advent of photoredox catalysis, an upsurge in the discovery of suitable radical precursors has been witnessed, and boron is becoming a protagonist in this field. Despite many studies focused on trifluoroborates, the use of boronic acids and esters have received much less attention in this regard. Because of their high oxidation potential, the development of methods to enable their involvement in photocatalyzed reactions is only recent. Nonetheless, this review summarizes novel strategies developed to unlock their role as radical precursors in photochemical reactions and discloses the potential that boronic acids and esters own, when their intrinsic chemical properties are exploited.

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Section: Radical Generation Through a Reductive Quenching Cyclementioning

confidence: 99%

Uncovering the Potential of Boronic Acid and Derivatives as Radical Source in Photo(electro)chemical Reactions

et al. 2022

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“…[131] In 2008, Denmark et al confirmed that Lewis bases can enhance the reactivity of electrophilic p-orbitals. [124] Inspired by this discovery, in 2019, they proposed a new strategy, [132] which carried out the free radical addition reaction of alkylboronic acids and esters with Baylis-Hillman adducts by a photocatalytic and Lewis base dual catalytic system. The substrate range was wide and the conditions were mild (Scheme 38).…”

Section: Combining Lewis Base Catalysis With Photoredox Catalysismentioning

confidence: 99%

Advanced Synthesis Using Photocatalysis Involved Dual Catalytic System

Guo

Wang

et al. 2022

Eur J Org Chem

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Combining visible‐light photoredox catalysis with other kinds of catalysis is a powerful strategy to address the barriers met in reactions driven by single catalyst. Under environmentally benign condition, photoredox catalysis produces radical species via visible light irradiation. These species then work with other catalysts, often resulting in unconventional reactivities, by which the scope of reaction could be expanded. Interest focusing on photocatalysis in the synthetic chemistry community has grown tremendously over the past five years, and one of the most striking emerging features is the development of dual catalytic approaches. This minireview summarizes the progress on this theme, mainly including dual catalytic systems merging photoredox activation with acid/base catalysts.

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“…29 In this case, the reduced nucleophilicity of the oxygen in 45 prevents the formation of the O-alkylated product, and therefore unprotected hydroxy C-nucleophiles can be directly used. Among the diverse cinchona alkaloids tested, quinidine (46) together with hydroquinone and molecular sieves gave the best results, affording a wide range of spirooxindoles 47 bearing contiguous tertiary and quaternary stereocentres in good to high yields and excellent diastereo-and enantiocontrol. While substitution with bulky nitrogen protecting group reduced the reactivity, groups with different electronic properties can be successfully accommodated in both aromatic rings.…”

Section: Scheme 6 Lewis Base Catalysed Allylic Amination/diels-alder mentioning

confidence: 99%

“…The same authors further expanded the visible-lightmediated -allylation of MBH carbonates 96 using alkylboronic acids 117 and esters 118 as radical precursors under Lewis-base/photoredox dual catalysis (Scheme 17B). 46 The transformation relies on the dynamic formation of the Lewis acid-base complex between the alkylboronic compound and DABCO (not shown), which subsequently undergoes SET oxidation by the Ir* 3+ photocatalyst to afford the corresponding alkyl radical 114. From this point, the mechanism proceeds in the same way as with organotrifluoroborate salts (Scheme 17A).…”

Section: Short Review Synthesis Scheme 17 Light-triggered Radical -Amentioning

confidence: 99%

Unconventional Transformations of Morita–Baylis–Hillman Adducts

Calcatelli

Cherubini‐Celli²,

Carletti³

et al. 2020

Synthesis

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Morita–Baylis–Hillman (MBH) adducts are versatile starting materials widely employed in Lewis base catalysis. A myriad of different transformations have been reported based on either allylic alkylations with stabilised nucleophiles or annulations with diverse dipolarophiles. Apart from these two conventional types of reactivity, MBH adducts have recently been implemented in alternative and complementary catalytic strategies, including: (i) one-pot and cascade transformations, where additional chemical bonds are formed following the asymmetric allylic alkylation event in a single synthetic operation; (ii) regioselective α-allylations for the synthesis of trisubstituted alkenes; and (iii) dual activation strategies, involving Lewis base catalysis together with transition metal complexes or light, enabling allylic alkylations with nonstabilised nucleophiles and cascade processes. The present Short Review summarises the most significant unconventional catalytic transformations of racemic MBH adducts reported within the last decade.1 Introduction2 Multi-Step Single-Vessel Transformations (path iii)2.1 One-Pot Transformations2.2 Cascade Transformations3 α-Allylations (path iv)3.1 SN2′ Mechanism3.2 SN2′–SN2 Mechanism3.3 Miscellaneous Mechanisms4 Dual Activation (path v)4.1 MBH Adduct as Electrophile4.2 MBH Adduct as Nucleophile5 Summary and Outlook

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The coupling of alkylboronic acids and esters with Baylis–Hillman derivatives by Lewis base/photoredox dual catalysis

Cited by 30 publications

References 46 publications

Uncovering the Potential of Boronic Acid and Derivatives as Radical Source in Photo(electro)chemical Reactions

Uncovering the Potential of Boronic Acid and Derivatives as Radical Source in Photo(electro)chemical Reactions

Advanced Synthesis Using Photocatalysis Involved Dual Catalytic System

Unconventional Transformations of Morita–Baylis–Hillman Adducts

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