- Cobalt-Catalyzed Aerobic Oxidative Cleavage of Alkyl Aldehydes: Synthesis of Ketones, Esters, Amides, and α-Ketoamides
-
A widely applicable approach was developed to synthesize ketones, esters, amides via the oxidative C?C bond cleavage of readily available alkyl aldehydes. Green and abundant molecular oxygen (O2) was used as the oxidant, and base metals (cobalt and copper) were used as the catalysts. This strategy can be extended to the one-pot synthesis of ketones from primary alcohols and α-ketoamides from aldehydes.
- Li, Tingting,Hammond, Gerald B.,Xu, Bo
-
supporting information
p. 9737 - 9741
(2021/05/31)
-
- Access to β-Ketonitriles through Nickel-Catalyzed Carbonylative Coupling of α-Bromonitriles with Alkylzinc Reagents
-
Herein, we report a nickel-catalyzed carbonylative coupling of α-bromonitriles and alkylzinc reagents with near stoichiometric carbon monoxide to give β-ketonitriles in good yields. The reaction is catalyzed by a readily available and stable nickel(II) pincer complex. The developed protocol tolerates substrates bearing a variety of functional groups, which would be problematic or incompatible with previous synthetic methods. Additionally, we demonstrate the suitability of the method for carbon isotope labeling by the synthesis of 13C-labeled β-ketonitriles and their transformation into isotopically labeled heterocycles.
- Donslund, Aske S.,Neumann, Karoline T.,Corneliussen, Nicklas P.,Grove, Ebbe K.,Herbstritt, Domenique,Daasbjerg, Kim,Skrydstrup, Troels
-
p. 9856 - 9860
(2019/07/09)
-
- Copper(I)-catalyzed enantioselective nucleophilic borylation of aldehydes: An efficient route to enantiomerically enriched α-alkoxyorganoboronate esters
-
The first catalytic enantioselective nucleophilic borylation of a
- Kubota, Koji,Yamamoto, Eiji,Ito, Hajime
-
supporting information
p. 420 - 424
(2015/01/30)
-
- Stereoselective synthesis of cyclopropanes based on a 1,2-chirality transfer
-
A stereoselective route to enantiomerically enriched bicyclic cyclopropane derivatives 13 is described which is based on a conceptually novel 1,2-chirality transfer approach. The hyperconjugative interaction of an electronically excited carbonyl group with the σ* orbital of an adjacent C-X bond in the transition state of a hydrogen abstraction causes the preference of a certain conformation and consequently the differentiation between two diastereotopic methylene groups. The 1,2-chirality transfer is completed by a subsequent HX elimination which destroys the only stereogenic center in the reactants 12. Furthermore, it was found that contrary enthalpic and entropic influences result in the existence of an inversion temperature T0. Upon crossing T0 the stereoselectivity is reversed. Considering this temperature dependency, chirality transfer efficiencies of up to 83% could be achieved. The absolute configuration of most products could be unambiguously determined by VCD spectroscopy combined with DFT calculations.
- Muehling, Olaf,Wessig, Pablo
-
supporting information; experimental part
p. 7951 - 7960
(2009/10/23)
-
- One-pot synthesis of imidazolines from aldehydes: detailed study about solvents and substrates
-
Imidazolines were prepared in one-pot operation from aldehydes and diamines through oxidation of aminal intermediates by NBS. This method could be applied to various aromatic and aliphatic aldehydes and N-nonsubstituted and N-monosubstituted 1,2-diamines. Furthermore, it was found that CH2Cl2 could be altered to TBME, a more environmentally friendly solvent, in the reaction using N-nonsubstituted 1,2-diamines. The reaction conditions were very mild and chemoselective.
- Fujioka, Hiromichi,Murai, Kenichi,Kubo, Ozora,Ohba, Yusuke,Kita, Yasuyuki
-
p. 638 - 643
(2007/10/03)
-
- Synthesis of diarylazepan-4-ones
-
Synthesis of several 3,3-diarylazepan-4-ones and 5,5-diarylazepan-4-ones has been established starting from two tetrasubstituted olefins, which is derived from commercially available piperidine-3-carboxylic acid ethyl ester and piperidine-4-carboxylic aci
- Chang, Meng-Yang,Kung, Yung-Hua,Ma, Chih-Chong
-
p. 199 - 202
(2007/10/03)
-
- Photochemical synthesis of highly functionalized cyclopropyl ketones
-
A series of di- and trisubstituted cyclopropyl ketones 11 were prepared by irradiation of ketones 3 and 5, which bear a leaving group adjacent to the carbonyl C-atom. The required ketones 3 could be easily synthesized either by functionalization of ketones 1 with a hypervalent iodine reagent, 2, or by O-sulfonylation of α-hydroxy ketones 7. The nitrates 5 were obtained by treatment of the corresponding α-bromo ketones with AgNO3. The irradiation of 3 and 5 must be performed in the presence of an acid scavenger (1-methyl-1H-imidazole) to obtain the cyclopropanes 11 in good yields. The synthetic efficiency of the method was, among other things, demonstrated by the preparation of a highly strained bicyclo[2.1.0]pentane 11i in good yield. The mechanism of the photochemical cyclization was investigated by means of photokinetic measurements, as well as by quantum-chemical calculations. It was shown that the presence of the leaving group substantially influences all steps of the photochemical reaction cascade. The X-ray crystal structures of 11j and exo-11k were also determined.
- Wessig, Pablo,Muehling, Olaf
-
p. 865 - 893
(2007/10/03)
-