TY  - THES
A1  - Wolf, Felix
T1  - Neuartige Olefine und Aryldiazoniumtetrafluoroborate für die MATSUDA-HECK-Reaktion
Y1  - 2016
ER  - 
TY  - JOUR
A1  - Schmidt, Bernd
A1  - Wolf, Felix
A1  - Ehlert, Christopher
T1  - Systematic Investigation into the Matsuda-Heck Reaction of alpha-Methylene Lactones: How Conformational Constraints Direct the beta-H-Elimination Step
JF  - The journal of organic chemistry
N2  - alpha-Methylene-gamma-butyrolactone and alpha-methylene-gamma-valerolactone undergo Pd-catalyzed Matsuda-Heck couplings with arene diazonium salts to alpha-benzyl butenolides or pentenolides, respectively, or to alpha-benzylidene lactones. The observed regioselectivity is strongly ring size dependent, with six-membered rings giving exclusively alpha-benzyl pentenolides, whereas the five-membered alpha-methylene lactone reacts to mixtures of regioisomers with a high proportion of (E)-alpha-benzylidene-gamma-butyrolactones. DFT calculations suggest that the reasons for these differences are not thermodynamic but kinetic in nature. The relative energies of the conformers of the Pd sigma-complexes resulting from insertion into the Pd-aryl bond were correlated with the dihedral angles between Pd and endo-beta-H. This correlation revealed that in the case of the six-membered lactone an energetically favorable conformer adopts a nearly synperiplanar Pd/endo-beta-H arrangement, whereas for the analogous Pd sigma-complex of the five-membered lactone the smallest Pd/endo-beta-H dihedral angle is observed for a conformer with a comparatively high potential energy. The optimized conditions for Matsuda-Heck arylations of exo-methylene lactones were eventually applied to the synthesis of the natural product anemarcoumarin A.
Y1  - 2016
U6  - https://doi.org/10.1021/acs.joc.6b02207
SN  - 0022-3263
VL  - 81
SP  - 11235
EP  - 11249
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Schmidt, Bernd
A1  - Wolf, Felix
A1  - Brunner, Heiko
T1  - Styrylsulfonates and -Sulfonamides through Pd-Catalysed Matsuda-Heck Reactions of Vinylsulfonic Acid Derivatives and Arenediazonium Salts
JF  - European journal of organic chemistry
N2  - Arene diazonium salts undergo Matsuda-Heck reactions with vinylsulfonates and -sulfonamides to give styrylsulfonic acid derivatives in high to excellent yields and with high to excellent selectivities. By quantifying the evolution of nitrogen over time in a gas-meter apparatus, the reactivities of ethylvinylsulfonate and the benchmark olefin methyl acrylate were compared for an electron-rich and an -deficient arene diazonium salt. Tertiary sulfonamides react in Matsuda-Heck couplings with high conversions, but require long reaction times, which prevents the determination of kinetic data through the measurement of nitrogen evolution. Secondary sulfonamides were found to be unreactive. From these results, the following order of reactivity could be deduced: H2C=CHCO2Me > H2C=CHSO2OEt > H2C=CHSO2N(Me)Bn >> H2C=CHSO2NHBn. Through the Matsuda-Heck coupling of 5-indolyldiazonium salt and a tertiary vinylsulfonamide, the synthesis of the C-5-substituted indole part of the antimigraine drug naratriptan was accomplished in high yield.
KW  - Homogeneous catalysis
KW  - Cross-coupling
KW  - Palladium
KW  - Sulfonamides
KW  - Alkenes
KW  - Drug design
Y1  - 2016
U6  - https://doi.org/10.1002/ejoc.201600469
SN  - 1434-193X
SN  - 1099-0690
SP  - 2972
EP  - 2982
PB  - Wiley-VCH
CY  - Weinheim
ER  -