617-92-5Relevant articles and documents
An efficient synthesis of tertiary amines from nitriles in aprotic solvents
Shares, Jonathan,Yehl, Jenna,Kowalsick, Amanda,Byers, Philip,Haaf, Michael P.
scheme or table, p. 4426 - 4428 (2012/09/25)
Tertiary amines are utilized extensively as non-nucleophilic proton scavengers for a number of organic transformations. Herein we report the efficient syntheses of tertiary alkyl amines from their corresponding alkyl nitriles in the presence of a heterogeneous palladium catalyst and a source of dihydrogen in aprotic solvents. The reaction is atom economic, the conditions are mild, and the isolated yields are virtually quantitative. The degree of amine alkylation shows some solvent dependency; in polar protic solvents such as ethanol or methanol, the reaction affords a mixture of products with the secondary alkyl amine as the major product.
Influence of the reaction temperature on the regioselectivity in the rhodium-catalyzed hydroformylation of vinylpyrroles
Caiazzo, Aldo,Settambolo, Roberta,Uccello-Barretta, Gloria,Lazzaroni, Raffaello
, p. 279 - 284 (2007/10/03)
The influence of the temperature on the regioselectivity in the hydroformylation of the vinylpyrrole isomers and of the corresponding N-tosylated substrates has been investigated in the range 20-100°C, in the presence of Rh4(CO)12. At all the temperatures the branched aldehyde was prevailing with respect to the linear isomer for all the substrates ( α-regioselectivity). With increasing temperature, an increase of the linear aldehyde was observed to a different extent in dependence on the substrate nature. 2H NMR investigation of the crude reaction mixture recovered from deuterioformylation of 3-vinylpyrrole at partial substrate conversion points out that the observed depression of the α-regioselectivity with increasing temperature must be connected to a β-hydride elimination process occurring for the branched alkyl-rhodium intermediates but not for the linear ones.
Gas-phase heteroaromatic substitution. 8. Electrophilic attack of ethyl cation on pyrrole, N-methylpyrrole, furan, and thiophene
Laguzzi,Bucci,Grandinetti,Speranza
, p. 3064 - 3068 (2007/10/02)
Ethyl cation, obtained in the dilute gas state, together with CH5+, from the γ-radiolysis of methane, has been allowed to react with pyrrole, N-methylpyrrole, furan, and thiophene, in the pressure range 50-760 Torr and in the presence of variable concentrations of a gaseous base (NMe3). The mechanism of the substitution and of the subsequent isomerization of the relevant ionic intermediates is discussed, and the intrinsic positional selectivity of the C2H5+ ions is evaluated. Gas-phase C2H5+ ion attack on pyrroles is characterized by a significant positional selectivity toward those substrate positions with the highest net negative charge (N:α:β = 13%:10%:77% for pyrrole; α:β = 19%:81% for N-methylpyrrole). Interaction of C2H5+ with the furan center having the maximum value of the negative charge, i.e. the O atom, favors occurrence of α-substitution (α:β = 57%:43%). Thiophene displays no significant positional discrimination (α:β = 54%:46%). Gas-phase attack of C2H5+ on simple five-membered heteroaromatics is mainly governed by electrostatic interactions established within the encounter pair. This characterizes gaseous C2H5+ as a very ''hard'' electrophile, rather than a borderline acid, as expected on the grounds of the alkyl cation ''hardness'' scale. This deviation is explained in terms of the bridged geometry for C2H5+ and its effect on the LUMO energy level of the ion.
