51308-10-2Relevant articles and documents
1,2-Diarylethanols by alternative regioselective reductive ring-opening of 2,3-diaryloxiranes
Blasio, Nadia Di,Lopardo, Maria Teresa,Lupattelli, Paolo
experimental part, p. 938 - 944 (2009/07/19)
Non-symmetrical £rans-2,3-diaryloxiranes have been regioselectively opened by catalytic hydrogenation over Pd/C, NaBH4/Pd and [Cp 2TiCl]/H2O. Although in the catalytic hydrogenation reactions the epoxides were mainly opened at the β-carbon with respect to the substituted aryl ring in all cases, with the [Cp2TiCl]/H 2O system the regioselectivity was affected by the electronic properties of the aryl residues, the epoxides being opened on the carbon bearing the most electron-releasing or the least electron-withdrawing group. With the NaBH4/Pd system different regioisomers were obtained depending on the substituents. Starting from enantioenriched epoxides, no loss of optical purity was observed in the alcohols formed.
Role of Alkali Halides in the Synthesis of Nitrogen Containing Heterocycles by Reductive Carbonylation of Aromatic Nitro-Derivatives Catalysed by Ru3(CO)12
Pizzotti, Maddalena,Cenini, Sergio,Quici, Silvio,Tollari, Stefano
, p. 913 - 918 (2007/10/02)
The presence of alkali halides as co-catalysts in the reductive carbonylation of o-nitrobiphenyl 1 catalysed by Ru3(CO)12 strongly increases the rate of reactions and slectivity towards heterocyclization products .With sodium halides, depending on the anion, the selectivity for carbazole is in the order Cl- > Br- ca.F- I-; whereas the selectivity for 5H-phenanthridin-6-one is the reverse I- > Br- ca.F- > Cl-.The influence of the cation can be explained with the polarization of a CO ligand of the ruthenium cluster, due to the interaction of the alkali cation with the oxygen lone pair.In fact high yields (>80percent) of heterocyclization products are obtained when the alkali cation is free to coordinate the CO.When this interaction is reduced, by sequestering the cation with crown-ethers, or better with cryptands, the yield of heterocyclic products is 14percent and 0percent respectively.The role of the anion and cation in the catalytic mechanism are discussed.The attempted extension of this reaction to other nitro-derivatives for the potential synthesis of aromatic heterocycles with larger rings are also reported.
Ruthenium-Catalyzed Dehydrogenative N-Heterocyclization: Indoles from 2-Aminophenethyl Alcohols and 2-Nitrophenethyl Alcohols
Tsuji, Yasushi,Kotachi, Shinji,Huh, Keun-Tae,Watanabe, Yoshihisa
, p. 580 - 584 (2007/10/02)
Indole derivatives 3 were readily obtained from 2-aminophenethyl alcohols 1 in the presence of 2 mol percent (based on 1) of RuCl2(PPh3)3 under reflux in toluene.Indole (3a) was afforded from 2-aminophenethyl alcohol (1a) quantitatively.Other indoles (3) were also obtained in 73-99percent isolated yields from the corresponding 1, which were easily prepared by condensation between the corresponding 2-nitrotoluenes and aldehydes followed by reduction.During the reaction, a stoichiometric amount of hydrogen was spontaneously evolved into the gas phase.With a heterogeneous and homogeneous binary catalyst system, indoles were afforded in one pot from 2-nitrophenethyl alcohols 2 under a hydrogen atmosphere.