- Chromium(II)-Catalyzed Diastereoselective and Chemoselective Csp2-Csp3 Cross-Couplings Using Organomagnesium Reagents
-
A simple protocol for performing chromium-catalyzed highly diastereoselective alkylations of arylmagnesium halides with cyclohexyl iodides at ambient temperature has been developed. Furthermore, this ligand-free CrCl2 enables efficient electrophilic alkenylations of primary, secondary, and tetiary alkylmagnesium halides with readily available alkenyl acetates. Moreover, this chemoselective C-C coupling reaction with stereodefined alkenyl acetates proceeds in a stereoretentive fashion. A wide range of functional groups on alkyl iodides and alkenyl acetates are well tolerated, thus furnishing functionalized Csp2-Csp3 coupling products in good yields and high diastereoselectivity. Detailed mechanistic studies suggest that the in situ generated low-valent chromium(I) species might be the active catalyst for these Csp2-Csp3 cross-couplings.
- Li, Jie,Ren, Qianyi,Cheng, Xinyi,Karaghiosoff, Konstantin,Knochel, Paul
-
supporting information
p. 18127 - 18135
(2019/11/19)
-
- Synthesis of a new conjugated polymer composed of pyrene and bithiophene units for organic solar cells
-
An alternating conjugated copolymer composed of pyrene and bithiophene units, poly(DHBT-alt-PYR) has been synthesized. The synthesized polymer was found to exhibit good solution processibility and thermal stability, losing less than 5% of their weight on heating to approximately 370 °C. The synthesized polymer showed its maximum absorption and peak PL emission at 401 and 548 nm, respectively. The optical band gap energy of the polymer was determined by absorption onset to be 2.64 eV. Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the polymer was determined to be-5.48 and-2.84 eV by cyclic voltametry (CV) and the optical band gap. The polymer photovoltaic devices were fabricated with a typical sandwich structure of ITO/PEDOT:PSS/active layer/LiF/Al using poly(DHBT-alt-PYR) as an electron donor and C60-PCBM or C70-PCBM as electron acceptors. The open circuit voltage, short circuit current and fill factor of the device using C70-PCBM as an acceptor were 0.75 V, 3.80 mA/cm 2 and 0.28, respectively, and the maximum power conversion efficiency of the device was 0.80%. Copyright
- Lee, Sun-Young,Jung, Choong-Hwa,Kang, Jun,Kim, Hee-Joon,Shin, Won Suk,Yoon, Sung Cheol,Moon, Sang-Jin,Lee, Changjin,Hwang, Do-Hoon
-
experimental part
p. 4367 - 4372
(2012/06/16)
-
- Method for producing alkyl-bridged ligand systems and transition metal compounds
-
The invention relates to a method for producing highly substituted alkyl-bridged ligand systems on the basis of indene derivatives and transition metal compounds. Said alkyl-bridged ligand systems can be obtained in high yields using this method.
- -
-
-
- Thermochemical Bond Dissociation Energies of Carbon-Magnesium Bonds
-
The heats of formation of 29 alkylmagnesium bromides, isobutyl bromide, and neopentyl bromide have been determined, and bond dissociation energies have been derived for the Grignard reagents.For saturated alkyl derivatives the C-Mg bond strength decreases with an increasing number of β-hydrogens in the series methyl, neopentyl, isobutyl, butyl, ethyl, 1-ethylpropyl, 1-methylpropyl, isopropyl, and t-butyl.Bonding in alkyl bromides and alkylmagnesium bromides is discussed.
- Holm, Torkil
-
p. 464 - 467
(2007/10/02)
-
