A Traceless Directing Group for CH Borylation

Preshlock, Sean; Plattner, Donald L.; Maligres, Peter E.; Krska, Shane W.; Maleczka, Robert E.; Smith, Milton R.

doi:10.1002/anie.201306511

Cited by 187 publications

(163 citation statements)

References 29 publications

(32 reference statements)

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“…Smith and Maleczka have recently shown that the N-H group of various heterocycles can be temporarily protected by N-H borylation with HBpin. 12 However, we were not able to achieve the borylation of indazole following this protocol. Consequently a series of different, less labile, nitrogen protecting groups were explored ( Table 1).…”

Section: Figure 1 C-h Borylation Of 2-fluoropyridinesmentioning

confidence: 93%

Multidirectional Synthesis of Substituted Indazoles via Iridium-Catalyzed C–H Borylation

et al. 2015

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Section: Figure 1 C-h Borylation Of 2-fluoropyridinesmentioning

confidence: 93%

Multidirectional Synthesis of Substituted Indazoles via Iridium-Catalyzed C–H Borylation

et al. 2015

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“…The reaction at the 4-position of pyrazoles results from borylation of the nitrogen, creating steric hindrance around the nonbasic nitrogen of this heterocycle, and a presumed higher barrier for C−H bond cleavage α to the basic nitrogen, as is seen in pyridine. 111,140 …”

Section: Arene Functionalization Without Directing Groupsmentioning

confidence: 99%

Evolution of C–H Bond Functionalization from Methane to Methodology

2015

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This Perspective presents the fundamental principles, the elementary reactions, the initial catalytic systems, and the contemporary catalysts that have converted C−H bond functionalization from a curiosity to a reality for synthetic chemists. Many classes of elementary reactions involving transition-metal complexes cleave C−H bonds at typically unreactive positions. These reactions, coupled with a separate or simultaneous functionalization process lead to products containing new C−C, C−N, and C−O bonds. Such reactions were initially studied for the conversion of light alkanes to liquid products, but they have been used (and commercialized in some cases) most often for the synthesis of the more complex structures of natural products, medicinally active compounds, and aromatic materials. Such a change in direction of research in C−H bond functionalization is remarkable because the reactions must occur at an unactivated C−H bond over functional groups that are more reactive than the C−H bond toward classical reagents. The scope of reactions that form C−C bonds or install functionality at an unactivated C−H bond will be presented, and the potential future utility of these reactions will be discussed.

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“…cross-coupling reaction, 8 Marder's Cu-catalyzed borylation reaction, 9 Maligre's Ir-catalyzed C−H bond activation reaction, 10 Hsu's aryl Grignard reagents or aryllithium species with trialkyl boronates, 11 Wang's transition-metal-free transformation from aromatic amines. 12 Although these procedures have shown some practical applications in synthesis, their application on a preparative scale has still been limited and deficient in view of laborious synthetic process, harsh reaction conditions, heavy metal contamination, with the result that it is difficult to meet the demands for large-scale preparation.…”

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confidence: 99%

A Practical and Scalable Process for the Preparation of 4-Aminophenylboronic Acid Pinacol Ester

Xue¹,

He²,

Li³

et al. 2014

HETEROCYCLES

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A practical process has been developed for scalable preparation of 4-aminophenylboronic acid pinacol ester through facile two-step procedure. After boron trifluoride etherate efficiently activated the reaction of 4-bromoaniline with diphenyl ketone, metalation reaction of protected 4-bromoaniline with lithium trialkylmagnesiate readily proceeded under mild conditions (−20 °C), which was subsequently subjected to esterification and deprotection reaction to give the 4-aminophenylboronic acid pinacol ester. The improved synthetic route has been successfully scaled up to kilogram quantities in good yield and high quality.Arylboronic acids and arylboronates have shown great importance due to their widespread applications in organic synthesis and other fields. 1,2 In particular, functionalized arylboronic acids and arylboronates are highly valuable because consecutive cross-coupling is possible from these compounds, which can rapidly construct the complex structure of target molecules. 3 Of these compounds, 4-aminophenylboronic acid pinacol ester is one of important arylboronates for its versatile applications in a wide variety of biologically active compounds, 4 for example piperazine-substituted s-triazine derivatives exhibiting various types of biological properties, such as antiHIV, antituberculosis, anticancer, antimycobacterial, etc. 5 In addition, the compound has also been successfully applied in synthesis of fluorescent sensors for heavy and soft metal ions such as mercury. 6 Up to now, some successes have been made in the preparation of 4-aminophenylboronic acid pinacol ester, 7 typical examples included Raj's Pd-catalyzed

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A Traceless Directing Group for CH Borylation

Cited by 187 publications

References 29 publications

Multidirectional Synthesis of Substituted Indazoles via Iridium-Catalyzed C–H Borylation

Multidirectional Synthesis of Substituted Indazoles via Iridium-Catalyzed C–H Borylation

Evolution of C–H Bond Functionalization from Methane to Methodology

A Practical and Scalable Process for the Preparation of 4-Aminophenylboronic Acid Pinacol Ester

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