19/11/2015

Dear Subscribers,

Below is our product and campaign information for this month. We hope you find them useful for your research.

Contents Highlights

Chemistry News - Professor’s abstract

The group of Professor Todd Marder (Julius Maximilian University of Würzburg) works on organometallic chemistry, homogeneous catalysis, luminescence, nonlinear optics, liquid crystals, crystal engineering, and small molecule triggers of stem cell differentiation. TCI is pleased to introduce their recent study on Zinc-Catalyzed Borylation of Primary, Secondary and Tertiary Alkyl Halides:
(We thank Prof. Marder and Dr. Bose for writing the abstract; for full article, please refer to the link below)

More information about “Dioxaborolane” reagents, e. g. Bis[(pinacolato)boryl]methane, can be found by searching “dioxaborolane” on TCI-website.

Alkyl Boronates from Alkyl Halides Research Article

Zinc-Catalyzed Borylation of Primary, Secondary and Tertiary Alkyl Halides with Alkoxy Diboron Reagents at Room Temperature


Angew. Chem. Int. Ed. 2014, 53, 1799-1803 and Angew. Chem. 2014, 126, 1829-1834.


Introduction:

Organoboronates are important in medicinal chemistry[1] and they are often used as synthetic intermediates for transition-metal catalyzed cross-coupling, conjugate addition and many other reactions.[2] Herein, a simple zinc-catalyzed route to primary, secondary and some tertiary alkylboronates using the diboron(4) reagents B2pin2 or B2neop2 (pin = pinacolato; neop = neopentaneglycolato) is reported. This follows the first report of any metal catalyzed borylation of alkyl halides, which used a copper catalyst,[3a] and our report of the Cu-catalyzed borylation of aryl halides.[3b]

Alkylboronates can be prepared easily by stirring an alkyl halide with a catalyst comprising ZnCl2 and the readily available N-heterocyclic carbene (NHC) ligand IMes (IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene), in the presence of a commercially available diboron(4) reagent and an appropriate base (either KOtBu or KOMe) in MTBE (MeOtBu) as the solvent at room temperature.

Scope:

1- Borylation of primary alkyl halides:

Primary alkyl halides having different functional groups such as ether, ketal, ester, cyano and alcohol groups were converted to the corresponding alkylboronates in good yields, in the presence of a Zn-catalyst at room temperature (Scheme 1).

2- Borylation of secondary alkyl halides:

As illustrated in Scheme 2, unactivated secondary alkyl halides can be smoothly borylated to provide the desired alkylboronates in excellent yields.

3- Borylation of tertiary alkyl halides:

In addition to primary and secondary alkyl electrophiles, ZnCl2/IMescan also catalyzed the borylation of some tertiary alkyl halides. Thus, reactions of 1-bromo and 1,3-dibromoadamantane gave the corresponding mono- and bis- boronates in moderate to good yields (Scheme 3).

Conclusion:

A new catalyst system, incorporating the inexpensive, earth-abundant and extremely low toxicity metal zinc, in the presence of a readily accessible NHC ligand is capable of borylating primary, secondary and even some tertiary alkyl iodides and bromides under mild conditions (room temperature). A related ZnBr2-NHC catalyst system also borylates aryl halides[4a] and, most recently, we have shown that ZnCl2, in the presence of 4,4’-di-tBu-bipyridine as ligand, borylates both aryl C-X bonds and the C-H bonds adjacent to them.[4b]

References:

[1] a) M. A. Beenen, C. An, J. A. Ellman, J. Am. Chem. Soc. 2008, 130, 6910-6911; b) L. J. Milo, J. H. Lai, Jr., W. Wu, Y. Liu, H. Maw, Y. Li, Z. Jin, Y. Shu, S. E. Poplawski, Y. Wu, D. G. Sanford, J. L. Sudmeier, W. W. Bachovchin, J. Med. Chem. 2011, 54, 4365-4377; c) H. Einsele, Rec. Results Cancer Res. 2010, 184, 173-187; d) M. Ilies, L. Di Costanzo, D. P. Dowling, K. J. Thorn, D. W. Christianson, J. Med. Chem. 2011, 54, 5432-5443; e) N. Suzuki, T. Suzuki, Y. Ota, T. Nakano, M. Kurihara, H. Okuda, T. Yamori, H. Tsumoto, H. Nakagawa, N. Miyata, J. Med. Chem. 2009, 52, 2909-2922.

[2] R. Jana, T. P. Pathak, M. S. Sigman, Chem. Rev. 2011, 111, 1417-1492; b) Boronic Acids: Preparation and Applications in Organic Synthesis, Medicine and Materials (Ed.: D. G. Hall), 2nd ed., Wiley-VCH, Weinheim, 2011.

[3] a) C.-T. Yang, Z.-Q. Zhang, H. Tajuddin, C.-C. Wu, J. Liang, J.-H. Liu, Y. Fu, M. Czyzewska, P. G. Steel, T. B. Marder, L. Liu, Angew. Chem. 2012, 124, 543-547; Angew. Chem. Int. Ed. 2012, 51, 528-532; b) C. Kleeberg, L. Dang, Z. Lin, T. B. Marder, Angew. Chem. 2009, 121, 5454-5458; Angew. Chem. Int. Ed. 2009, 48, 5350-5354.

[4] a) S. K. Bose, T. B. Marder, Org. Lett. 2014, 16, 4562-4565; b) S. K. Bose, A. Bießenberger, A. Eichhorn, P. G. Steel, Z. Lin, T. B. Marder, Angew. Chem. 2015, 127, ASAP. DOI: 10.1002/ange.201505603; Angew. Chem. Int. Ed. 2015, 54, ASAP. DOI: 10.1002/anie.201505603.

TCI News

Savings on Electronic Materials and Solar Cell Research Reagents (valid for November & December 2015)

Customers receive a 7.5% discount on their orders for Electronic Materials and Solar Cells Research reagents.

(Please note TCI’s website displays the reduced campaign price.)


Orders through TCI eShop are eligible for an extra 5% discount.

The product selection covers around 2000 different compounds in the following categories:


Solar Cell Research Reagents

Secondary Battery Reagents

Organic Light-Emitting Diode (OLED) Materials

Organic Transistor Materials

Molecular Conductors

Building Blocks for Semiconducting Polymers

Building Blocks for Small Molecule Semiconductors

Ligands for Functional Metal Complexes


This is just a small selection of TCI’s 25,000+ reagents.

For more information, please visit our website or contact your local TCI Office.

[New Pamphlet] Asymmetric Organocatalysts

This brochure contains the organocatalysts that make metal-free asymmetric synthesis possible. This is suitable for green chemistry oriented research.

- covers various organocatalysts such as proline analogs, amino acids and Cinchona Alkaloids
- also covers organocatlysts with axial chirality and chiral phase-transfer catalysts

[New Edition] TCIMail Quarterly Magazine – No. 167

In the TCIMAIL, we mainly introduce our new reagents in the fields of Synthetic Organic Chemicals, Analytical Chemistry and Materials Chemistry. Examples of application and use are explained in an easy way to understand using various schemes and charts. The TCIMAIL also contains technical papers contributed by leading professors and scientists.
Chemistry Chat
- Focusing on the Elements - Compounds Composed of Two Elements (3)
Kentaro Sato

Applications
- Graphene Oxide
- Difluoromethylating Reagents
- Building Blocks for Click Chemistry
- Cyclin-Dependent Kinases Inhibitor
- SIRT1 Inhibitor
- Adenylate Cyclase Activator

Synthetic Chemistry

Research Article

A Novel Cyanation Reaction of Arenes Using Acetonitrile as a Cyano Source

Shen et al. have reported a novel cyanation reaction of arenes using acetonitrile as a cyano source. According to their results, the reaction proceeds through a tandem process producing aryl iodides (1) from a copper complex catalyst-promoted iodination of simple arenes with N-iodosuccinimide (NIS), and a subsequent cyanation reaction. In this reaction, it is presumed that the cyano source is generated via the formation of an acetonitrile-derived cyanomethyl group-substituted TEMPO intermediate (2) and a sequential C-CN bond cleavage by the action of copper complex catalysts and hexamethyldisilane. This cyanation-process using TEMPO, copper complex catalysts and acetonitrile as a cyano source is a safe and inexpensive synthetic method and its future development can be expected.

Product Highlight

A Useful Crystalline Trifluoroacetylating Reagent

(Trifluoroacetyl)benzotriazole (1) is a crystalline trifluoroacetylating reagent and used for the direct trifluoroacetylation of amines and alcohols without any base. The trifluoroacetylation with amines is carried out at room temperature in good yields when primary and secondary amines and low nucleophilic aniline derivatives are employed as reactants. On the other hand, the trifluoroacetylation with alcohols proceeds with refluxing THF. All primary and secondary alcohols and phenols including such a high-acidic phenol as 4-nitrophenol are available for this trifluoroacetylation. 1 has advantages of a crystalline solid and is easy to weigh, and can be used for the direct introduction of a trifluoroacetyl group under mild conditions. Thus, 1 is a useful trifluoroacetylating reagent.

New products

Bioscience

New Products

Mixed-Mode columns (ODS + Ion-Exchange) for HPLC “TCI Dual series”

• Analysis of Preservatives by TCI Dual ODS-AX10 (Anion-Exchange column)

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