Metal-free syn-dioxygenation of alkenes

Rawling, Michael J.; Tomkinson, Nicholas C. O.

doi:10.1039/c3ob27387c

Cited by 67 publications

(41 citation statements)

References 56 publications

(24 reference statements)

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“…[3] To further improve the process, some metal-free strategies have also been achieved by using stoichiometric peroxides, hypervalent iodine and selenium (Scheme 1, process b). [4] Despite the tremendous progress, a greener and more practical dioxygenation method is still highly demanded. Organic electrochemistry represented as an ideal synthetic technology has experienced a renaissance, [5] owning to the reason that electrons can be directly manipulated via the electrochemical oxidation and reduction.…”

Section: Abstract: Electrochemistry; Oxidation; Dimethoxylation; Olefinsmentioning

confidence: 99%

Substrate‐Dependent Electrochemical Dimethoxylation of Olefins

Zhang

et al. 2018

Adv Synth Catal

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A general and direct electrochemical dimethoxylation of olefins is reported, which enables a divergent route to different products depending on the structure of olefins. The present protocol features mild conditions and broad substrate scope (49 examples) obviating the usage of transtion-metals and external oxidants. More importantly, to rationalize the divergent route of the transformation, an ionic-like pathway involving carbocation intermediate is proposed and the diverse products is attributed to the different stability of carbocations.

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Section: Abstract: Electrochemistry; Oxidation; Dimethoxylation; Olefinsmentioning

confidence: 99%

Substrate‐Dependent Electrochemical Dimethoxylation of Olefins

Zhang

et al. 2018

Adv Synth Catal

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“…[3] Selenium dioxide is often used for selective allylic hydroxylation. [1,5,6] In connection with this reaction, epoxidation of alkenes followed by hydration is used to prepare trans-1,2-diols. [1,5,6] In connection with this reaction, epoxidation of alkenes followed by hydration is used to prepare trans-1,2-diols.…”

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confidence: 99%

Direct Synthesis of 1,4‐Diols from Alkenes by Iron‐Catalyzed Aerobic Hydration and CH Hydroxylation

2014

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Various 1,4-diols are easily accessible from alkenes through iron-catalyzed aerobic hydration. The reaction system consists of a user-friendly iron phthalocyanine complex, sodium borohydride, and molecular oxygen. Furthermore, the effect of additional ligands on the iron complex was examined for a model reaction. The second hydroxy group is installed by direct C(sp(3))-H oxygenation, which is based on a [1,5] hydrogen shift process of a transient alkoxy radical that is formed by formal hydration of the olefin.

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“…[17] [Fe II (L3)(OTf) 2 ]-catalyzed AD of (Z)-alkenes,( Z)-bmethyl styrene,i ndene,d ihydronaphthalene,c oumarin, and 2-cyclohexene-1-one,g ave the corresponding cis-diols in 22.6-83.1 % ee (entries 1-5, Table 2). Incorporation of 18 Ointo I was not observed in the presence of H 2 18 O (Figure 3b), but both the oxygen atoms of I were 18 O-labeled if H 2 18 O 2 was used ( Figure 3c). Fort erminal alkenes, tert-butyl acrylate gave the cis-diol in nearly quantitative yield with 92.3 % ee (entry 6, Table 2);1 -octene,h omoallyl benzene,a nd cyclohexyl ethylene afforded the cis-diols in 81.6-84.9 % ee and with high selectivity (94-96 %, entries 7-9, Figure S3).…”

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confidence: 98%

“…[1] To date,m etal-free reagents for alkene cisdihydroxylation remain underdeveloped; [2] examples include cyclic peroxide anhydrides, [3a] or chiral hypervalent iodine(III). This "[Fe II (L)(OTf) 2 ] + H 2 O 2 "m ethod is applicable to both (E)alkenes and terminal alkenes (24 examples > 80 %ee, up to 1g scale).…”

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confidence: 99%

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Highly Enantioselective Iron‐Catalyzed cis‐Dihydroxylation of Alkenes with Hydrogen Peroxide Oxidant via an Fe^III‐OOH Reactive Intermediate

Zang

Liu

et al. 2016

Angewandte Chemie

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The development of environmentally benign catalysts for highly enantioselective asymmetric cis-dihydroxylation (AD) of alkenes with broad substrate scope remains ac hallenge.B ye mploying [Fe II (L)(OTf) 2 ]( L = N,N'dimethyl-N,N'-bis(2-methyl-8-quinolyl)-cyclohexane-1,2-diamine) as ac atalyst, cis-diols in up to 99.8 %e ew ith 85 % isolated yield have been achieved in AD of alkenes with H 2 O 2 as an oxidant and alkenes in al imiting amount. This "[Fe II (L)(OTf) 2 ] + H 2 O 2 "m ethod is applicable to both (E)alkenes and terminal alkenes (24 examples > 80 %ee, up to 1g scale). Mechanistic studies,i ncluding 18 O-labeling,U V/Vis, EPR, ESI-MS analyses,a nd DFT calculations lend evidence for the involvement of chiral Fe III -OOH active species in enantioselective formation of the two CÀOb onds.Asymmetric cis-dihydroxylation (AD) of alkenes,u sually using osmium reagents,i sa ni mportant reaction in organic synthesis. [1] To date,m etal-free reagents for alkene cisdihydroxylation remain underdeveloped; [2] examples include cyclic peroxide anhydrides, [3a] or chiral hypervalent iodine(III). [3b] On the other hand, notable progress has been achieved for alkene cis-dihydroxylation with non-osmium metal compounds, [1d, 4] including that of ruthenium, [4b, 5] manganese, [4d, 6, 7] and iron. [4a,c,d, 8] However,t here are only af ew examples of AD reactions catalyzed by complexes of the earth-abundant metals iron [9] and manganese. [10,11] An enantioselectivity of > 90 % ee was reported for a-[Fe II (R,R-6-Me 2 -BPBP)(OTf) 2 ]-catalyzed AD of electron-rich alkenes (E)-2-octene and (E)-2-heptene (96-97 % ee); the method, which was developed by Que and co-workers,employed H 2 O 2 as at erminal oxidant and alkenes in a5 0-fold excess. [9b] [Mn II (S,S-BQCN)Cl 2 ]-catalyzed AD of electron-deficient (E)-alkenes with Oxone (five examples,9 3-96 % ee)h ave been reported in our previous work. [11] It has been proposed that non-heme iron-catalyzed alkene cis-dihydroxylation reactions proceed via intermediate Fe III (OOH), [12] Fe V (O)(OH), [12,13] Fe IV (OH) 2 , [14] or Fe II (OOH) [15] as active oxidant, depending on the ligand systems employed. Herein, we describe the realization of iron-catalyzed AD reactions with ar easonably broad substrate scope and with alkene substrates used in al imiting amount, [8b,c] yielding cis-diols in up to 99.8 % ee (85 %i solated yield) when H 2 O 2 is used as at erminal oxidant. An enantioselectivity of > 95 % ee was achieved for 14 examples spanning both electron-deficient and electron-rich (E)-alkenes.Achiral Fe III (OOH) reactive intermediate is suggested to be responsible for the highly enantioselective AD reactions.Thet etradentate N 4 ligands L2, L4, and L6 (featuring different chiral diamine backbones compared to that of R,R-BQCN (L1)), [16] along with L1 derivatives L3, L5, L7, and L8, were synthesized according to ar eported method (see Figure 1a nd the Supporting Information). Tr eatment of these ligands with [Fe(OTf) 2 ·(MeCN) 2 ]i nT HF afforded [Fe II (L)(OTf) 2 ]( L= L...

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Metal-free syn-dioxygenation of alkenes

Cited by 67 publications

References 56 publications

Substrate‐Dependent Electrochemical Dimethoxylation of Olefins

Substrate‐Dependent Electrochemical Dimethoxylation of Olefins

Direct Synthesis of 1,4‐Diols from Alkenes by Iron‐Catalyzed Aerobic Hydration and CH Hydroxylation

Highly Enantioselective Iron‐Catalyzed cis‐Dihydroxylation of Alkenes with Hydrogen Peroxide Oxidant via an Fe^III‐OOH Reactive Intermediate

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Metal-free syn-dioxygenation of alkenes

Cited by 67 publications

References 56 publications

Substrate‐Dependent Electrochemical Dimethoxylation of Olefins

Substrate‐Dependent Electrochemical Dimethoxylation of Olefins

Direct Synthesis of 1,4‐Diols from Alkenes by Iron‐Catalyzed Aerobic Hydration and CH Hydroxylation

Highly Enantioselective Iron‐Catalyzed cis‐Dihydroxylation of Alkenes with Hydrogen Peroxide Oxidant via an FeIII‐OOH Reactive Intermediate

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Highly Enantioselective Iron‐Catalyzed cis‐Dihydroxylation of Alkenes with Hydrogen Peroxide Oxidant via an Fe^III‐OOH Reactive Intermediate