- Transition Metal Catalyst-Free, Base-Promoted 1,2-Additions of Polyfluorophenylboronates to Aldehydes and Ketones
-
A novel protocol for the transition metal-free 1,2-addition of polyfluoroaryl boronate esters to aldehydes and ketones is reported, which provides secondary alcohols, tertiary alcohols, and ketones. Control experiments and DFT calculations indicate that both the ortho-F substituents on the polyfluorophenyl boronates and the counterion K+ in the carbonate base are critical. The distinguishing features of this procedure include the employment of commercially available starting materials and the broad scope of the reaction with a wide variety of carbonyl compounds giving moderate to excellent yields. Intriguing structural features involving O?H???O and O?H???N hydrogen bonding, as well as arene-perfluoroarene interactions, in this series of racemic polyfluoroaryl carbinols have also been addressed.
- Budiman, Yudha P.,Friedrich, Alexandra,Kole, Goutam Kumar,Liu, Zhiqiang,Luo, Xiaoling,Marder, Todd B.,Radius, Udo,Tian, Ya-Ming,Westcott, Stephen A.
-
p. 16529 - 16538
(2021/06/23)
-
- London Dispersion Interactions Rather than Steric Hindrance Determine the Enantioselectivity of the Corey–Bakshi–Shibata Reduction
-
The well-known Corey–Bakshi–Shibata (CBS) reduction is a powerful method for the asymmetric synthesis of alcohols from prochiral ketones, often featuring high yields and excellent selectivities. While steric repulsion has been regarded as the key director of the observed high enantioselectivity for many years, we show that London dispersion (LD) interactions are at least as important for enantiodiscrimination. We exemplify this through a combination of detailed computational and experimental studies for a series of modified CBS catalysts equipped with dispersion energy donors (DEDs) in the catalysts and the substrates. Our results demonstrate that attractive LD interactions between the catalyst and the substrate, rather than steric repulsion, determine the selectivity. As a key outcome of our study, we were able to improve the catalyst design for some challenging CBS reductions.
- Eschmann, Christian,Song, Lijuan,Schreiner, Peter R.
-
supporting information
p. 4823 - 4832
(2021/02/01)
-
- Asymmetric Hydrogenation of Aryl Perfluoroalkyl Ketones Catalyzed by Rhodium(III) Monohydride Complexes Bearing Josiphos Ligands
-
The asymmetric hydrogenation of 2,2,2-trifluoroacetophenones and aryl perfluoroalkyl ketones was developed using a unique, well-defined chloride-bridged dinuclear rhodium(III) complex bearing Josiphos-type diphosphine ligands. These complexes were prepared from [RhCl(cod)]2, Josiphos ligands, and hydrochloric acid. As catalyst precursors, they allow for the efficient and enantioselective synthesis (up to 99 % ee) of chiral secondary alcohols with perfluoroalkyl groups. This system does not require an activating base for the hydrogenation of 2,2,2-trifluoroacetophenones. Additionally, the enantioselective C=O hydrogenations of 2-phenyl-3-(haloacetyl)-indoles, a class of privileged structures in medicinal chemistry, is reported for the first time.
- Brüning, Fabian,Nagae, Haruki,K?ch, Daniel,Mashima, Kazushi,Togni, Antonio
-
supporting information
p. 10818 - 10822
(2019/07/31)
-
- N-heterocyclic carbene-catalysed pentafluorophenylation of aldehydes
-
N-heterocyclic carbenes have been utilized as highly efficient organocatalysts to catalyse multifluorophenylation of aldehydes with pentafluorophenyltrimethylsilane or bis(trimethylsilyl)tetrafluorobenzene to afford the corresponding fluorinated adducts in 49-99% yields.
- Du, Guang-Fen,Xing, Fen,Gu, Cheng-Zhi,Dai, Bin,He, Lin
-
p. 35513 - 35517
(2015/05/05)
-
- Perfluoroalkyl and -aryl Zinc Ate Complexes: Generation, Reactivity, and Synthetic Application
-
A combination of dimethylzinc, perfluoroalkyl iodide, and LiCl afforded a new type of perfluoroalkyl (RF) zinc ate complex. These complexes show much greater thermal stability than conventional perfluorinated metal species, such as RF-lithium species and Grignard reagents, and they can be used at room temperature or higher. The results of DFT calculations on the origin of the enhanced stability are reported and the synthetic utility of RF-zincate complexes is demonstrated. The magnificent ate: A combination of dimethylzinc, perfluoroalkyl iodide, and LiCl afforded a new type of perfluoroalkyl (RF) zinc ate complex. These complexes show greater thermal stability than conventional perfluorinated metal species and they can be used at room temperature or higher. The results of DFT calculations on the origin of the enhanced stability are reported and the synthetic utility of RF-zincate complexes is demonstrated.
- Wang, Xuan,Hirano, Keiichi,Kurauchi, Daisuke,Kato, Hisano,Toriumi, Naoyuki,Takita, Ryo,Uchiyama, Masanobu
-
supporting information
p. 10993 - 10996
(2015/11/10)
-
- Copper-bisphosphine-initiated pentafluorophenylation of aldehydes and ketones
-
In the presence of substoichiometric quantities of a copper-bisphosphine complex, a variety of aldehydes and reactive ketones undergo pentafluorophenylation using pentafluorophenyl-trimethylsilane. Georg Thieme Verlag Stuttgart.
- Brogan, Samatha,Carter, Neil B.,Lam, Hon Wai
-
supporting information; experimental part
p. 615 - 617
(2010/09/18)
-
- Reactions of salicylaldehyde with tris(pentafluorophenyl)silanes and secondary amines
-
Reactions of tris(pentafluorophenyl)silanes RSi(C6F 5)3 with salicylaldehyde and secondary amines were studied. The reactions afforded α-pentafluorophenyl-substituted amines. Silanes RSi(C6F5)3 (R = Me, Ph, C 6F5, CH2CH=CH2, and CH=CH 2) were found to be efficient reagents for transfer of the C 6F5 group to the iminium cation generated from salicylaldehyde and amine. However, tris(pentafluorophenyl)phenylethynyl-and tris(pentafluorophenyl)silanes were not able to serve as a source of a fluorinated substituent because of competitive transfer of acetylenide fragment or hydride.
- Dilman,Arkhipov,Belyakov,Struchkova,Tartakovsky
-
p. 517 - 522
(2007/10/03)
-
- Bromine-magnesium-exchange as a general tool for the preparation of polyfunctional aryl and heteroaryl magnesium-reagents
-
The scope of the Br-Mg-exchange reaction for the preparation of polyfunctional aryl and heteroaryl magnesium reagents has been studied. Various functional groups (ester, cyano, bromide) were tolerated in the exchange reaction allowing the preparation of polyfunctional Mg-reagents. Several dibromo- or tribromoheterocycles undergo a chemoselective mono-Br-Mg exchange leading to highly functionalized heterocycles.
- Abarbri, Mohamed,Dehmel, Florian,Knochel, Paul
-
p. 7449 - 7453
(2007/10/03)
-
- Benzene derivatives and a liquid-crystalline medium
-
The invention relates to novel benzene derivatives of the formula I STR1 in which n is 0, 1, 2, 3, 4, 5, 6 or 7, Q is --O--, --CH=CH-- or a single bond, r is 0, 1, 2, 3, 4 or 5, s is 0, 1 or 2, X is F, Cl, OCHF2 or CF3, L is H or F, and A is STR2 Z, Z-Ar, Ar-Z, Z-Cyc in which Z is a single bond, --(CH2)2 -- or --(CH2)4 --, Ar is 1,4-phenylene or biphenyl-4,4'-diyl and Cyc is trans-1,4-cyclohexylene.
- -
-
-
- Fluoride Ion-Catalyzed Generation and Carbonyl Addition of α-Halo Carbanions Derived from α-Halo Organosilicon Compounds
-
The title carbanion species are generated from the corresponding α-haloorganosilicon compounds by the action of a catalytic amount of tris(diethylamino)sulfonium difluorotrimethylsilicate and are found to undergo addition to aldehyde carbonyl efficiently at ambient temperature.The synthetic potential of the reaction is demonstrated by application to the synthesis of some insecticides.
- Fujita, Makoto,Obayashi, Michio,Hiyama, Tamejiro
-
p. 4135 - 4146
(2007/10/02)
-