Sodium perborate: a mild and convenient reagent for efficiently oxidizing organoboranes

Kabalka, George W.; Shoup, Timothy M.; Goudgaon, Ν. M.

doi:10.1021/jo00286a026

Cited by 154 publications

(95 citation statements)

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“…Standard procedures for hydroboration and oxidation gave complex product mixtures from reactions of bis-BOC-protected adenine derivatives 21j and 21l 77,78. However, hydroboration of the monomethoxytrityl(MMTr)-protected adenine derivatives 26a and 26b , followed by oxidation of the resulting alkylboranes in the presence of basic hydrogen peroxide gave MMTr-protected ( R )-3-(6-amino-9 H -purin-9-yl)-3-phenylpropan-1-ol) 27a and MMTr-protected ( S )-3-(6-amino-9 H -purin-9-yl)hexan-1-ol 27b in 82% and 77% yield (Equation 2).…”

Section: Results and Disscussionmentioning

confidence: 99%

Regio- and Enantioselective N-Allylations of Imidazole, Benzimidazole, and Purine Heterocycles Catalyzed by Single-Component Metallacyclic Iridium Complexes

2009

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Highly regio-and enantioselective iridium-catalyzed N-allylations of benzimidazoles, imidazoles, and purines have been developed. N-Allylated benzimidazoles and imidazoles were isolated in high yields (up to 97%) with high branched-to-linear selectivity (up to 99:1) and enantioselectivity (up to 98% ee) from the reactions of benzimidazole and imidazole nucleophiles with unsymmetrical allylic carbonates in the presence of single component, ethylene-bound, metallacyclic iridium catalysts. NAllylated purines were also obtained in high yields (up to 91%) with high N9:N7 selectivity (up to 96:4), high branched-to-linear selectivity (98:2), and high enantioselectivity (up to 98% ee) under similar conditions. The reactions encompass a range of benzimidazole, imidazole, and purine nucleophiles, as well as a variety of unsymmetrical aryl, heteroaryl, and aliphatic allylic carbonates. Competition experiments between common amine nucleophiles and the heterocyclic nitrogen nucleophiles studied in this work illustrate the effect of nucleophile pK a on the rate of iridiumcatalyzed N-allylation reactions. Kinetic studies on the allylation of benzimidazole catalyzed by metallacyclic iridium-phosphoramidite complexes, in combination with studies on the deactivation of these catalysts in the presence of heterocyclic nucleophiles, provide insight into the effects of the structure of the phosphoramidite ligands on the stability of the metallacyclic catalysts. The data obtained from these studies has led to the development of N-allylations of benzimidazoles and imidazoles in the absence of an exogenous base.

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Section: Results and Disscussionmentioning

confidence: 99%

Regio- and Enantioselective N-Allylations of Imidazole, Benzimidazole, and Purine Heterocycles Catalyzed by Single-Component Metallacyclic Iridium Complexes

2009

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“…Oxidative hydroboration of the side chain of nitrosafrol led to an alcohol at C-3'. Nitrosafrol was oxidized using BH 3 ·DMS/THF/NaBO 3 ·4H 2 O/H 2 O as previously described for other alkenes and alkynes 11 . The primary alcohol 7 was obtained with a 53.1% w/w yield and the secondary alcohol 8 with 2.4% yield (scheme 1).…”

Section: Resultsmentioning

confidence: 99%

“…As in the previous oxidation, the primary alcohol 5 was obtained with a 59.4% and the secondary alcohol 6 with 1.1%w/w yield 11,[16][17][18] (scheme 1). In In the 1 H NMR spectrum of isomer 8, the presence of signal at d = 4.11 ppm (m, 1H') was to assigned at carbinolic hydrogen in C-2' position (secondary alcohol).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Nine Safrole Derivatives and Their Antiproliferative Activity Towards Human Cancer Cells

Espinoza

Madrid

Liber

et al. 2010

J. Chil. Chem. Soc.

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Safrole from sassafras oil (Ocotea pretiosa Mez., Lauraceae), is an abundant natural product showing interesting functionality and chemical structure. Starting from safrole, nine derivatives were prepared and assessed for antiproliferative effect using different human cell lines. The in vitro growth inhibition assay was based on the sulphorhodamine dye to quantify cell viability. Some safrole derivatives, (2E)-3-(3',4'-methylenedioxi)phenyl acrylaldehyde (3) and 4-allyl-5-nitrobenzene-1,2-diol (4) presented better antiproliferative effect than the parent compound on two breast cancer cell lines (MCF-7 and MDA-MB-231) and one human colorectal cancer cell line (DLD-1) with IC 50 values of 55.0 + 7.11 µM, 37.5 + 2.65 µM and 44.0 + 6.92 µM, respectively, without toxicity towards dermal human fibroblast (DHF cells).

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“…Therefore, isolation of the dearomatization products (5a) was carried out after oxidation of 3a to confirm the product structure (see Supporting Information). 18 Several other NHC ligands were also tested in the reaction, including IMes, IPr, and SIPr, but they all resulted in low yields (Table 1, Entries 24). The yield significantly decreased when the bisphosphine type ligands Xantphos and (R,R)-L1 were used in the reaction, although they were effective for the protoborylation of indoles in our previous work (Table 1, Entries 5 and 6).…”

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confidence: 99%

Copper(I)-catalyzed Diastereoselective Dearomative Carboborylation of Indoles

Hayama¹,

Kubota²,

Iwamoto³

et al. 2017

Chem. Lett.

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The first CB bond-forming dearomative carboborylation of heteroaromatic compounds has been achieved using copper(I) catalysis. This reaction includes the regioselective addition of a borylcopper(I) intermediate to indoles, followed by the diastereoselective methylation of the resulting copper(I) enolate intermediate to afford the corresponding 3-boryl-2-methylindolines bearing a quaternary stereogenic center with excellent regio-and diastereoselectivity.

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Sodium perborate: a mild and convenient reagent for efficiently oxidizing organoboranes

Cited by 154 publications

References 0 publications

Regio- and Enantioselective N-Allylations of Imidazole, Benzimidazole, and Purine Heterocycles Catalyzed by Single-Component Metallacyclic Iridium Complexes

Regio- and Enantioselective N-Allylations of Imidazole, Benzimidazole, and Purine Heterocycles Catalyzed by Single-Component Metallacyclic Iridium Complexes

Synthesis of Nine Safrole Derivatives and Their Antiproliferative Activity Towards Human Cancer Cells

Copper(I)-catalyzed Diastereoselective Dearomative Carboborylation of Indoles

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