TY  - JOUR
A1  - Budiman, Yudha P.
A1  - Lorenzen, Sabine
A1  - Liu, Zhiqiang
A1  - Radius, Udo
A1  - Marder, Todd B.
T1  - Base‐Free Pd‐Catalyzed C−Cl Borylation of Fluorinated Aryl Chlorides
JF  - Chemistry – A European Journal
N2  - Catalytic C−X borylation of aryl halides containing two ortho‐fluorines has been found to be challenging, as most previous methods require stoichiometric amounts of base and the polyfluorinated aryl boronates suffer from protodeboronation, which is accelerated by ortho‐fluorine substituents. Herein, we report that a combination of Pd(dba)2 (dba=dibenzylideneacetone) with SPhos (2‐dicyclohexylphosphino‐2’,6’‐dimethoxybiphenyl) as a ligand is efficient to catalyze the C‐Cl borylation of aryl chlorides containing two ortho‐fluorine substituents. This method, conducted under base‐free conditions, is compatible with the resulting di‐ortho‐fluorinated aryl boronate products which are sensitive to base.
KW  - boronate ester
KW  - borylation
KW  - cross-coupling
KW  - fluoroarene
KW  - palladium-catalyzed
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225687
VL  - 27
IS  - 11
SP  - 3869
EP  - 3874
ER  - 
TY  - JOUR
A1  - Huang, Mingming
A1  - Wu, Zhu
A1  - Krebs, Johannes
A1  - Friedrich, Alexandra
A1  - Luo, Xiaoling
A1  - Westcott, Stephen A.
A1  - Radius, Udo
A1  - Marder, Todd B.
T1  - Ni-Catalyzed Borylation of Aryl Sulfoxides
JF  - Chemistry—A European Journal
N2  - A nickel/N-heterocyclic carbene (NHC) catalytic system has been developed for the borylation of aryl sulfoxides with B\(_{2}\)(neop)\(_{2}\) (neop=neopentyl glycolato). A wide range of aryl sulfoxides with different electronic and steric properties were converted into the corresponding arylboronic esters in good yields. The regioselective borylation of unsymmetric diaryl sulfoxides was also feasible leading to borylation of the sterically less encumbered aryl substituent. Competition experiments demonstrated that an electron-deficient aryl moiety reacts preferentially. The origin of the selectivity in the Ni-catalyzed borylation of electronically biased unsymmetrical diaryl sulfoxide lies in the oxidative addition step of the catalytic cycle, as oxidative addition of methoxyphenyl 4-(trifluoromethyl)phenyl sulfoxide to the Ni(0) complex occurs selectively to give the structurally characterized complex trans-[Ni(ICy)\(_{2}\)(4-CF\(_{3}\)-C\(_{6}\)H\(_{4}\)){(SO)-4-MeO-C\(_{6}\)H\(_{4}\)}] 4. For complex 5, the isomer trans-[Ni(ICy)\(_{2}\)(C\(_{6}\)H\(_{5}\))(OSC\(_{6}\)H\(_{5}\))] 5-I was structurally characterized in which the phenyl sulfinyl ligand is bound via the oxygen atom to nickel. In solution, the complex trans-[Ni(ICy)\(_{2}\)(C\(_{6}\)H\(_{5}\))(OSC\(_{6}\)H\(_{5}\))] 5-I is in equilibrium with the S-bonded isomer trans-[Ni(ICy)\(_{2}\)(C\(_{6}\)H\(_{5}\))(SOC\(_{6}\)H\(_{5}\))] 5, as shown by NMR spectroscopy. DFT calculations reveal that these isomers are separated by a mere 0.3 kJ/mol (M06/def2-TZVP-level of theory) and connected via a transition state trans-[Ni(ICy)\(_{2}\)(C\(_{6}\)H\(_{5}\))(η\(^{2}\)-{SO}-C\(_{6}\)H\(_{5}\))], which lies only 10.8 kcal/mol above 5.
KW  - Boron
KW  - cross-coupling
KW  - N-heterocyclic carbenes
KW  - nickel
KW  - borylation
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256778
VL  - 27
IS  - 31
ER  - 
TY  - JOUR
A1  - Liu, Xiaocui
A1  - Ming, Wenbo
A1  - Luo, Xiaoling
A1  - Friedrich, Alexandra
A1  - Maier, Jan
A1  - Radius, Udo
A1  - Santos, Webster L.
A1  - Marder, Todd B.
T1  - Regio‐ and Stereoselective Synthesis of 1,1‐Diborylalkenes via Brønsted Base‐Catalyzed Mixed Diboration of Alkynyl Esters and Amides with BpinBdan
JF  - European Journal of Organic Chemistry
N2  - The NaOtBu‐catalyzed mixed 1,1‐diboration of terminal alkynes using the unsymmetrical diboron reagent BpinBdan (pin = pinacolato; dan = 1,8‐diaminonaphthalene) proceeds in a regio‐ and stereoselective fashion affording moderate to high yields of 1,1‐diborylalkenes bearing orthogonal boron protecting groups. It is applicable to gram‐scale synthesis without loss of yield or selectivity. The mixed 1,1‐diborylalkene products can be utilized in Suzuki–Miyaura cross‐coupling reactions which take place selectivly at the C–B site. DFT calculations suggest the NaOtBu‐catalyzed mixed 1,1‐diboration of alkynes occurs through deprotonation of the terminal alkyne, stepwise addition of BpinBdan to the terminal carbon followed by protonation with tBuOH. Experimentally observed selective formation of (Z)‐diborylalkenes is supported by our theoretical studies.
KW  - boronate esters
KW  - borylation
KW  - cross‐coupling
KW  - synthesis design
KW  - structure elucidation
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-214728
VL  - 2020
IS  - 13
SP  - 1941
EP  - 1946
ER  -