428819-24-3Relevant academic research and scientific papers
Selective Benzylic CH-Borylations by Tandem Cobalt Catalysis
Bauer, Matthias,Ghosh, Pradip,Jacobi von Wangelin, Axel,Schoch, Roland
supporting information, (2021/11/27)
Metal-catalyzed C?H activations are environmentally and economically attractive synthetic strategies for the construction of functional molecules as they obviate the need for pre-functionalized substrates and minimize waste generation. Great challenges reside in the control of selectivities, the utilization of unbiased hydrocarbons, and the operation of atom-economical dehydrocoupling mechanisms. An especially mild borylation of benzylic CH bonds was developed with the ligand-free pre-catalyst Co[N(SiMe3)2]2 and the bench-stable and inexpensive borylation reagent B2pin2 that produces H2 as the only by-product. A full set of kinetic, spectroscopic, and preparative mechanistic studies are indicative of a tandem catalysis mechanism of CH-borylation and dehydrocoupling via molecular CoI catalysts.
Stereoselective Desymmetrization of gem-Diborylalkanes by “Trifluorination”
Kumar, Nivesh,Reddy, Reddy Rajasekhar,Masarwa, Ahmad
supporting information, p. 8008 - 8012 (2019/05/28)
An efficient and general method for the chemoselective synthesis of unsymmetrical gem-diborylalkanes is reported. This method is based on a late-stage desymmetrization through nucleophilic “trifluorination”, providing chiral gem-diborylalkanes bearing a trifluoroborate group. The reaction offers a highly modular and diastereoselective approach towards the synthesis of gem-diborylcyclopropanes. The utility of the gem-diborylalkane building blocks was demonstrated by selective post-functionalization of the trifluoroborate group. These functionalizations include inter- and intra- Pd-catalyzed Suzuki–Miyaura coupling reactions.
Cobalt-Catalyzed C-H Borylation of Alkyl Arenes and Heteroarenes Including the First Selective Borylations of Secondary Benzylic C-H Bonds
Jayasundara, Chathurika R. K.,Sabasovs, Dmitrijs,Staples, Richard J.,Oppenheimer, Jossian,Smith, Milton R.,Maleczka, Robert E.
supporting information, p. 1567 - 1574 (2018/06/04)
A cobalt di-tert-butoxide complex bearing N-heterocyclic carbene (NHC) ligands has been synthesized and characterized. This complex is effective at catalyzing the selective monoborylation of the benzylic position of alkyl arenes using pinacolborane (HBpin) as the boron source. This same cobalt complex enables selective monoborylation of N-methylpyrrole, N-methylpyrazole, and N-methylindole. Catalysis can be achieved with as little as 2-3 mol % of the cobalt precatalyst at 80 °C.
Transition-metal-free synthesis of 1,1-diboronate esters with a fully substituted benzylic center via diborylation of lithiated carbamates
Zhao, Haonan,Tong, Min,Wang, Haijun,Xu, Senmiao
supporting information, p. 3418 - 3422 (2017/04/26)
A transition-metal-free lithiation-borylation method has been developed to access a variety of 1,1-diboronate esters with a fully substituted benzylic center from readily available secondary benzylic N,N-diisopropyl carbamates. The method is applicable to scale-up synthesis of 1,1-diboron compounds. Furthermore, the current method is also applicable to synthesizing optically active 1,1-silylboronate esters.
On the scope of the Pt-catalyzed Srebnik diborylation of diazoalkanes. An efficient approach to chiral tertiary boronic esters and alcohols via B-stabilized carbanions
Wommack, Andrew J.,Kingsbury, Jason S.
supporting information, p. 3163 - 3166 (2014/05/20)
Conditions milder than those previously reported are shown to be generally applicable to the Pt-catalyzed insertion of non-carbonyl-stabilized diazoalkanes into B2pin2. Selective transformation of one (pinacolato)boryl unit in the products is enabled by rapid, low-temperature deboronation in the presence of a Lewis base and genesis of a highly reactive B-stabilized carbanion.
Copper-catalyzed synthesis of 1,1-diborylalkanes through regioselective dihydroboration of terminal alkynes
Lee, Sumin,Li, Dingxi,Yun, Jaesook
supporting information, p. 2440 - 2443 (2014/11/08)
The copper-catalyzed sequential hydroboration of terminal alkynes with pinacolborane to prepare 1,1-diborylalkanes directly from alkynes was studied. Protected propargyl amines, propargyl alcohol derivatives, and simple alkynes regioselectively produced t
Novel C1-bridged bisboronate derivatives by insertion of diazoalkanes into bis(pinacolato)diborane(4)
Ali, Hijazi Abu,Goldberg, Israel,Kaufmann, Dieter,Burmeister, Christian,Srebnik, Morris
, p. 1870 - 1876 (2008/10/08)
The insertion reaction of bis(pinacolato)diborane(4) [(Me4C2O2)BB(O2C2Me4 ), 1] with various diazoalkanes provided novel representatives of a new class of substituted C1-bridged bis(pinacolato)diborane(4) derivatives 5a, 5b, 5c, and 5d in a range of 75-78% isolated yields. The reaction was efficiently catalyzed by Pt(PPh3)4 in toluene at 110 °C. Single-crystal X-ray diffraction, GCMS, and NMR multinuclear spectroscopies fully confirmed the structure and configuration of the new compounds. Crystals of 5a and 5c are centrosymmetric, while those of 5d are chiral. 5b crystallized with a somewhat unusual Fdd2 space symmetry. While its crystals are noncentrosymmetric, they contain mirror-related species. The degree of puckering of the five-membered C2O2B rings, as well as the dihedral angles between the mean planes of these rings, vary from one compound to another and to some extent from one ring to another within the same compound.
