Copper-catalyzed regioselective hydroboration of terminal alkynes in aqueous medium

Stereoselective Semi-Hydrogenations of Alkynes by First-Row (3d) Transition Metal Catalysts

The chemo- and stereoselective semi-hydrogenation of alkynes to alkenes is a fundamental transformation in synthetic chemistry, for which the use of precious 4d or 5d metal catalysts is well-established. In mankind's unwavering quest for sustainability, research focus has considerably veered towards the 3d metals. Given their high abundancy and availability as well as lower toxicity and noxiousness, they are undoubtedly attractive from both an economic and an environmental perspective. Herein, we wish to present noteworthy and groundbreaking examples for the use of 3d metal catalysts for diastereoselective alkyne semi-hydrogenation as we embark on a journey through the first-row transition metals.

Regio- and Stereoselective Syn-Boronation of Terminal Alkynes Catalyzed by Copper Nanospheres on Graphene Nanosheets

Evenly distributed copper nanospheres on reduced graphene oxide were prepared and showed high heterogeneous catalytic activity in converting varying terminal alkynes into (E)-β-styrene boronate esters. The excellent catalytic performance was achieved through the synergistic catalysis between Cu nanospheres and rGO. This work not only is a supplement for preparing (E)-β-styrene boronate esters but also provides a way for the rational designing of high-performance graphene-based catalysts. Meanwhile, the advancement of graphene-based nanomaterials will be motivated to promote their applications in the development of green catalytic chemistry.

Spectral data for the synthesis of (E)-alkenylboronic acid pinacol esters via hydroboration of alkynes

This data article is related to a research paper entitled “Solvent- and metal-free hydroboration of alkynes under microwave irradiation” (Gioia et al. TETL-D-19-01698) [1]. Herein we present the spectral data acquired from the synthesis of (E)-alkenyl boronic acid pinacol esters. The data include the general information and the synthetic procedure affording the target derivatives, which were fully characterized by Nuclear Magnetic Resonance (¹H and ¹³C NMR) and, for the most part, by Electrospray Ionization High Resolution Mass (ESI-MS). Proton and carbon NMR spectra and ESI-MS spectra were provided which will be useful for further organic chemists if they are interested in the synthesis of these building blocks.

Ligand-free, catalytic and regioselective hydroboration of selenoalkynes

The copper-catalyzed hydroboration of selenoalkynes in a regio- and stereoselective fashion is reported, delivering selenium-containing vinylboronate products in good yields.

Copper-boryl mediated organic synthesis

Organoboron compounds are valuable synthetic intermediates that find application in a diverse variety of processes including both C-X and C-C bond-forming transformations. This has been achieved by using a variety of boron derivatives. Of these, boronate esters are probably the most versatile and, reflecting this, methods for the generation of boronate esters are of considerable current interest. Given the mild reaction conditions, good functional group tolerance, and low cost of the metal catalyst, the use of copper-boryl reagents is particularly attractive. In this review, methodologies in copper-boryl chemistry are discussed and the many different transformations possible are surveyed.

Substrate-Assisted, Transition-Metal-Free Diboration of Alkynamides with Mixed Diboron: Regio- and Stereoselective Access to trans-1,2-Vinyldiboronates

A substrate-assisted diboration of alkynamides using the unsymmetrical pinacolato-1,8-diaminonaphthalenato diboron (pinBBdan) is described. The transition-metal-free reaction proceeds in a regio- and stereoselective fashion to exclusively afford trans-vinyldiboronates in good to excellent yields. Notably, Bdan and Bpin are installed on the α- and β-carbon atoms, respectively.

Copper-catalyzed highly selective approach to 2-boroallylic silanes from allenylsilanes

A highly selective copper-catalyzed borylcupration of 1,2-allenylsilanes affords 2-borylallylsilanes with many synthetically attractive functional groups by applying BIPHEP as the ligand has been developed.

A non-dissociative open-flask hydroboration with ammonia borane: ready synthesis of ammonia-trialkylboranes and aminodialkylboranes

Under open-flask conditions, ammonia borane hydroborates olefins in refluxing tetrahydrofuran. Unlike conventional hydroboration, the Lewis base (ammonia) is not dissociated from the boron center. Terminal alkenes selectively provide ammonia-trialkylborane complexes. On the other hand, internal alkenes afford aminodialkylboranes via a metal-free hydroboration-dehydrogenation sequence. Alkaline hydrogen peroxide oxidation of the products provides the corresponding alcohols in high yields.

Copper-catalyzed hydroboration of propargyl-functionalized alkynes in water

The Cu-catalyzed hydroboration of alkynes in operationally simple and environmentally friendly conditions is reported.