Rhodium catalysed dehydrogenative borylation of alkenes: Vinylboronates via C-H activation

We present herein a high yield, highly selective catalytic synthesis of vinylboronate esters (VBEs), including 1,1-disubstituted VBEs, from alkenes without significant hydrogenation or hydroboration, using the simple catalyst precursor, trans-[RhCl(CO)(PPh3)(2)] (1), and the diboron reagents B(2)pin(2) (2a, pin = pinacolato = OCMe2CMe2O) or B(2)neop(2) (2b, neop = neopentylglycolato = OCH2CMe2CH2O), or the monoboron reagent HBpin, all of which are commercially available. The reactions were conducted at 80 degrees C using conventional heating, or in a microwave reactor at 150 degrees C

Structural Versatility of Pyrene-2-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolane) and Pyrene-2,7-bis(4,4,5,5-tetramethyl-[1,3,2]dioxaborolane)

Three polymorphs of pyrene-2,7-bis­(Bpin)₂ (<b>1</b>) and two of pyrene-2-(Bpin) (<b>2</b>), where Bpin = 4,4,5,5-tetramethyl-[1,3,2]­dioxaborolane, two different 1:1 co-crystals of <b>1</b> with toluene, and co-crystals of hexafluorobenzene (HFB) with <b>1</b> (of highly unusual 2:1 composition) and <b>2</b> (of usual 1:1 composition) were isolated, studied by X-ray diffraction and differential scanning calorimetry, and described using Hirshfeld surfaces and two-dimensional fingerprint plots. Centrosymmetric phases β- and γ-<b>1</b> have densities respectively lower and higher than the chiral α-<b>1</b>; α- and β-<b>2</b> have different packing modes, both with <i>Z</i>′ = 3. Compound <b>1</b> is prone to form channel host–guest structures, for example, α- and β-<b>1·</b>PhMe and <b>1</b>·2HFB. The drastically different stabilities of α- and β-<b>1·</b>PhMe are discussed. The complex <b>2·</b>HFB has a mixed-stack packing motif. The structural versatility of <b>1</b> and <b>2</b> is explained by synthon frustration between structurally incongruent pyrene and Bpin moieties

Diboron(4) Compounds: From Structural Curiosity to Synthetic Workhorse

This article is also available through American Chemical Society Authorchoice Open Access at http://dx.doi.org/10.1021/acs.chemrev.6b00193Although known for over 90 years, only in the past two decades has the chemistry of diboron(4) compounds been extensively explored. Many interesting structural features and reaction patterns have emerged, and more importantly, these compounds now feature prominently in both metal-catalyzed and metal-free methodologies for the formation of B-C bonds and other processes.T.B.M. thanks the DFG and the University of Würzburg for support. S.A.W. thanks Chris Vogels for helpful discussions and NSERC of Canada for support