- Enantioselective cross-coupling of meso -epoxides with aryl halides
-
The first enantioselective cross-electrophile coupling of aryl bromides with meso-epoxides to form trans-β-arylcycloalkanols is presented. The reaction is catalyzed by a combination of (bpy)NiCl2 and a chiral titanocene under reducing conditions. Yields range from 57 to 99% with 78-95% enantiomeric excess. The 30 examples include a variety of functional groups (ether, ester, ketone, nitrile, ketal, trifluoromethyl, sulfonamide, sulfonate ester), both aryl and vinyl halides, and five- to seven-membered rings. The intermediacy of a carbon radical is strongly suggested by the conversion of cyclooctene monoxide to an aryl [3.3.0]bicyclooctanol.
- Zhao, Yang,Weix, Daniel J.
-
supporting information
p. 3327 - 3340
(2015/03/30)
-
- Synthetic spirocyclic endoperoxides: New antimalarial scaffolds
-
Here we report the development of a straightforward synthetic procedure for the preparation of spirocyclic endoperoxides as synthetic analogues of the natural product dihydroplakortin. The peroxides presented here are more potent antiplasmodials than dihydroplakortin itself and we proved for the first time their antimalarial activity in vivo. This journal is
- Brindisi, Margherita,Gemma, Sandra,Kunjir, Sanil,Di Cerbo, Luisa,Brogi, Simone,Parapini, Silvia,D'Alessandro, Sarah,Taramelli, Donatella,Habluetzel, Annette,Tapanelli, Sofia,Lamponi, Stefania,Novellino, Ettore,Campiani, Giuseppe,Butini, Stefania
-
supporting information
p. 357 - 362
(2015/03/31)
-
- Comparison of the catalytic activity of [(η5-C 5H5)Ru(2,2′-bipyridine)(L)]OTf versus [(η5-C5H5)Ru(6,6′-diamino-2,2′- bipyridine)(L)]OTf (L = labile ligand) in the hydrogenation of cyclohexanone. Evidence for the presence of a metal-ligand bifunctional mechanism under acidic conditions
-
The two title complexes as well as the dimeric complex [Ru(II) (η5-C5H5)(6,6′-diamino-2,2′- bipyridine)]2(OTf)2 have been synthesized and characterized by NMR and single-crystal X-ray crystallography. The direct structural comparison of the 2,2′-bipyridine and 6,6′-diamino-2, 2′-bipyridine complexes suggests that the electronic and steric environments of the ruthenium centers in both complexes are essentially equivalent, providing for a unique opportunity to probe the influence of the noncoordinated amine substituent on the relative reactivity and catalytic activity of the complexes. Opposite to what would be anticipated on the basis of steric effects, the bulkier amine-substituted ligand results in a catalyst showing substantially higher activity in the hydrogenation of cyclohexanone in acidic medium, which is attributed to the operation of a metal-ligand bifunctional hydrogenation mechanism mediated by the amine substituents in their protonated form acting as proton shuttles.
- Dimondo, Domenico,Thibault, Michelle E.,Britten, James,Schlaf, Marcel
-
p. 6541 - 6554
(2013/12/04)
-
- Dehydrogenation of alcohols by bis(phosphinite) benzene based and bis(phosphine) ruthenocene based iridium pincer complexes
-
Dehydrogenation of alcohols by three iridium pincer complexes, IrH(Cl)[2,6-(tBu2PO)2C6H 3] (1), {IrH(acetone)[2,6-(tBu2PO) 2C6H3]}{BF4} (2), and IrH(Cl)[{2,5-(tBu2PCH2)2C 5H2}Ru(C5H5)] (3), is reported, in both the presence and the absence of a sacrificial hydrogen acceptor. Dehydrogenation of secondary alcohols proceeds in a catalytic mode with turnover numbers up to 3420 (85% conversion) for acceptorless dehydrogenation of 1-phenylethanol. Primary alcohols are readily decarbonylated even at room temperature to give catalytically inactive 16e Ir-CO adducts. The mechanism of this transformation was studied in detail, especially for EtOH; new intermediates were isolated and characterized.
- Polukeev, Alexey V.,Petrovskii, Pavel V.,Peregudov, Alexander S.,Ezernitskaya, Mariam G.,Koridze, Avthandil A.
-
p. 1000 - 1015
(2013/05/08)
-
- Comparative dehydrogenation of cyclohexanol to cyclohexanone with commercial copper catalysts: Catalytic activity and impurities formed
-
Catalytic dehydrogenation of cyclohexanol to cyclohexanone has been carried out on phase gas in a continuous fixed bed reactor under atmospheric pressure. Copper chromite and copper zinc oxide catalysts have been checked. Effect of temperature (in the range 250-290 °C) and spatial time in reactor have been studied. The catalytic activity has been evaluated in terms of cyclohexanone yields and impurities from secondary reactions of dehydration and dehydrogenation of cyclohexanol have also been identified and quantified by GC/MS. Catalysts have been characterized by X-ray diffraction, temperature programmed desorption of ammonia and BET surface area measurement. High activity was confirmed by copper-based catalysts under the operating conditions, concerning the size and dispersion of the copper specie. It was also found that catalysts with alumina and chromium exhibit higher dehydration capacity, being cyclohexene the main impurity obtained. For a given cyclohexanone yield the impurities from dehydrogenation reactions showed similar trends for the three catalysts tested. Phenol was the main impurity obtained by dehydrogenation.
- Romero, Arturo,Santos, Aurora,Escrig, Daniel,Simón, Ernesto
-
experimental part
p. 19 - 27
(2011/11/07)
-
- Cis,tans-1,1′-Bicyclohexenyl: Confomer-dependent chemistry in benezene and in methanol
-
cis,trans-1,1′-Bicyclohexenyl (ct-BCH) from BCH triplets is a strained ground-state molecule that reverts to cis,cis-1,1′-bicyclohexenyl and the tricyclo[6.4.0.02,7]-cis-7,8-dodec-1-ene (CB) in benzne or methanol and the 1-(1-cyclohexenyl)-1-me
- Saltil, Jack,Marchand, Gary R.
-
p. 2702 - 2708
(2007/10/02)
-
- One-Pot Synthesis of Substituted Homoallylic Alcohols (3-Alkenols) and 1-Deuterio-3-alkenols; II. Extension to Ketone Enolates
-
The reaction of different lithium ketone enolates with α-chloro carbonyl compounds followed by in situ reduction with lithium aluminium hydride or deuteride and final lithiation with lithium powder leads to the corresponding homoallylic or 1-deuterio homoallylic alcohols in a regioselective manner.
- Barluenga, Jose,Alvarez, Flora,Concellon, Jose M.,Bernad, Pablo,Yus, Miguel
-
p. 318 - 320
(2007/10/02)
-