Organoboron Compounds, and the Study of Reaction Mechanisms. Primary Aliphatic Boronic Acids<sup>1</sup>

Snyder, H. R.; Kuck, J. A.; Johnson, John R.

doi:10.1021/ja01268a033

Cited by 146 publications

(66 citation statements)

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“…Thus, 3ef was subjected to oxidation conditions to give the corresponding ketone 4 (Scheme 4). 16 Some of the alkenylboronates (3ab, 3ef, and 3p) were assayed in Suzuki reactions, affording the expected tetrasubstituted alkenes 5 in good yields, stereoselectively (Scheme 5). 17 No isomerisation to conjugated dienes was observed.…”

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confidence: 99%

Ligand-controlled divergent formation of alkenyl- or allylboronates catalyzed by Pd, and synthetic applications

et al. 2014

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The use of different ligands allows the preparation of either allyl-or alkenylboronates by Pd-catalyzed borylation of allylic carbonates containing alkyne groups. Unprecedented borylative cyclisation to alkenylboronates takes place with PCy 3 . The difficult dissociation of NHC ligands allows borylation of carbonates in the presence of alkynes. Oxidation, regioselective Suzuki coupling, as well as Au-catalyzed cycloisomerisation of boronates illustrate the potential synthetic applications of these reactions.Boronates are important synthetic reagents. They are stable and compatible with most functional groups and are environmentally friendly, tolerating oxygen and water. A wide variety of boronates can be used as nucleophilic partners in Suzuki cross-coupling reactions and allylboronates are reactive towards aldehydes and imines, just to cite the most common uses of these compounds. 1 For this reason, the development of methods for the preparation of boronates, avoiding the use of highly nucleophilic and basic reagents is of main interest. On the other hand, enynes constitute versatile starting materials for the formation of carbo and heterocycles, 2 skeletal rearrangements, 3 and alkoxy-cyclisation, 4 among other reactions. During the last few years, Pd-catalyzed borylative cyclisation reactions of polyunsaturated species have been developed by our group 5-9 and Bäckvall's group, 10 with the aim of preparing cyclized boronates. Our seminal work described an unprecedented preparation of homoallylic boronates starting with 1,6-enynes, in which esters substituting the allylic position were tolerated (Scheme 1, top). 5,11 In our previous studies, addition of ligands precluded the incorporation of the boron substituent. Now, we have found conditions in which the choice of the appropriate ligand allows control of the borylation of alkyne-containing allylcarbonates, affording simple Miyaura coupling to allylboronates, or unprecedented formation of alkenylboronates by borylative cyclisation, a method which is complementary to alkyne hydroboration and the usual reactions of strongly basic Li and Mg nucleophiles with B(OMe) 3 .Thus, we started our study by reacting enynes containing an allylic carbonate group (1). In our previous work mentioned above, 5 we reported that reactions of acetates or other ester derivatives, under ligandless conditions, took place without activation of the C-O bond, leading to homoallylic boronates containing the unreacted ester group (Scheme 1, top). Reactions in the presence of phosphines led to simple cycloisomerisation without incorporation of the boryl group.In contrast, reaction of carbonates 1a-l with B 2 (pin) 2 in the presence of Pd(OAc) 2 and the IMes ligand (formed in situ by deprotonation of the imidazolium chloride with t-BuOK) in xylene, afforded the corresponding allylboronates (Table 1). The reaction is fast (less than 30 min) and takes place under optimum conditions (50 1C) in the absence of added base, as usual for carbonates. A variety of starting compounds showing different ...

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confidence: 99%

Ligand-controlled divergent formation of alkenyl- or allylboronates catalyzed by Pd, and synthetic applications

et al. 2014

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“…36 Arylboronic acids, which also reactive in this manner, are more robust: 37 thus the possibility of replacing the n-butyl with a phenyl group was examined. In Figure 7, it is clear that the B-n-butylboronic acid is far more effective in generating a fluorescent signal than B-phenylboronic acid.…”

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confidence: 99%

Urushiol Detection using a Profluorescent Nitroxide

et al. 2012

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A method to visually detect minute amounts of urushiol, the toxic catechol from poison oak, poison ivy, and poison sumac, has been developed utilizing the reaction of a profluorescent nitroxide with the B-n-butylcatecholboronate ester formed in situ from urushiol and B-n-butylboronic acid. The resulting N-alkoxyamine is strongly fluorescent upon illumination with a fluorescent lamp, allowing the location of the toxic urushiol contamination to be visualized. This methodology constitutes the groundwork for the future development of a spray to detect urushiol to avoid contact dermatitis, as well as to detect catecholamines for biomedical applications.

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“…Suzuki coupling of borylated binaphthyl systems the literature, even under anhydrous conditions [18] . Route I for the synthesis of 13 yielded 9% of 7a and 8% of 14, whereas route II yielded 2% of 7a and 23% of 14.…”

Section: Resultsmentioning

confidence: 99%

Suzuki Coupling of Chiral 1,1′-Binaphthyl Systems − New Synthetic Routes to Functionalize the 2- and 2,2′-Positions

Schilling¹,

Kaufmann²

1998

Eur. J. Org. Chem.

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1,1′‐Binaphthyl derivatives 1‐5, substituted in the 2‐ or 2,2′‐positions are used in palladium‐catalyzed Suzuki coupling reactions. The mono‐ and bis‐borylated coupling components 2, 4 and 5 can easily be prepared and purified, are air‐stable and are therefore interesting starting materials for Suzuki coupling reactions with several aryl halides. Thus a variety of new axially‐chiral 2‐ and 2,2′‐arylated 1,1′‐binaphthyls can be synthesized. Selective monoarylation of 3, 4 and 5 can be performed. Subsequent and stepwise arylation offers general access to unsymmetrically substituted binaphthyls. Moreover, interesting atropisomeric complex molecules, such as 4,4′‐bis[2‐(1,1′‐binaphthyl)]‐1,1′‐biphenyl (18a), are accessible. Compounds of type 18, which can be obtained by twofold Pd‐catalyzed coupling reactions, are of high potential value as ligands or promoters in catalytic, asymmetric processes or as chiral precursor molecules for host‐guest interactions.

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Organoboron Compounds, and the Study of Reaction Mechanisms. Primary Aliphatic Boronic Acids¹

Cited by 146 publications

References 0 publications

Ligand-controlled divergent formation of alkenyl- or allylboronates catalyzed by Pd, and synthetic applications

Ligand-controlled divergent formation of alkenyl- or allylboronates catalyzed by Pd, and synthetic applications

Urushiol Detection using a Profluorescent Nitroxide

Suzuki Coupling of Chiral 1,1′-Binaphthyl Systems − New Synthetic Routes to Functionalize the 2- and 2,2′-Positions

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Organoboron Compounds, and the Study of Reaction Mechanisms. Primary Aliphatic Boronic Acids1

Cited by 146 publications

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Ligand-controlled divergent formation of alkenyl- or allylboronates catalyzed by Pd, and synthetic applications

Ligand-controlled divergent formation of alkenyl- or allylboronates catalyzed by Pd, and synthetic applications

Urushiol Detection using a Profluorescent Nitroxide

Suzuki Coupling of Chiral 1,1′-Binaphthyl Systems − New Synthetic Routes to Functionalize the 2- and 2,2′-Positions

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Organoboron Compounds, and the Study of Reaction Mechanisms. Primary Aliphatic Boronic Acids¹