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First selective direct mono-arylation of piperidines using ruthenium-catalyzed C-H activation.

Schwarz MC, Dastbaravardeh N, Kirchner K, Schnürch M, Mihovilovic MD - Monatsh. Chem. (2013)

Bottom Line: A Ru-catalyzed mono-arylation in α-position of saturated cyclic amines is reported employing a C-H activation protocol.Substitution of the pyridine directing group with a bulky group, e.g., trifluoromethyl in the 3-position, proved to be crucial to avoid bis-arylation.Additionally, the directing group can be cleaved, taking advantage of an unprecedented detrifluoromethylation reaction.

View Article: PubMed Central - PubMed

Affiliation: Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9/163-OC, 1060 Vienna, Austria.

ABSTRACT

Abstract: A Ru-catalyzed mono-arylation in α-position of saturated cyclic amines is reported employing a C-H activation protocol. Substitution of the pyridine directing group with a bulky group, e.g., trifluoromethyl in the 3-position, proved to be crucial to avoid bis-arylation. This highly selective transformation can be performed with different amines and arylboronate esters. Additionally, the directing group can be cleaved, taking advantage of an unprecedented detrifluoromethylation reaction.

No MeSH data available.


Related in: MedlinePlus

Optimized PBE1PBE geometry of the equilibrium structure of 3a
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Fig1: Optimized PBE1PBE geometry of the equilibrium structure of 3a

Mentions: As the reaction does not seem to be very tolerant regarding different rings, it was hypothesized that a specific geometry seems to be essential. Therefore, energy-minimization calculations were conducted for 3a, 3b, 3c, 3d, 3g, 3i, and 3j. The six-membered rings, except for the 2-substituted piperidine 3b, all have rather similar geometry according to the calculations. As shown in Fig. 1 for 3a, they all have a slightly twisted boat conformation at the piperidine core. Especially the piperidine ring of 3a and the 4-substituted piperidine ring of 3d show very similar properties, and therefore the difference in yield could not be explained by the calculated geometries of these starting materials. A more conclusive result could have been obtained by calculating the corresponding Ru complexes formed during the reaction. However, since the nature of the active catalyst species is not known entirely, no such calculations could be conducted.Fig. 1


First selective direct mono-arylation of piperidines using ruthenium-catalyzed C-H activation.

Schwarz MC, Dastbaravardeh N, Kirchner K, Schnürch M, Mihovilovic MD - Monatsh. Chem. (2013)

Optimized PBE1PBE geometry of the equilibrium structure of 3a
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4494768&req=5

Fig1: Optimized PBE1PBE geometry of the equilibrium structure of 3a
Mentions: As the reaction does not seem to be very tolerant regarding different rings, it was hypothesized that a specific geometry seems to be essential. Therefore, energy-minimization calculations were conducted for 3a, 3b, 3c, 3d, 3g, 3i, and 3j. The six-membered rings, except for the 2-substituted piperidine 3b, all have rather similar geometry according to the calculations. As shown in Fig. 1 for 3a, they all have a slightly twisted boat conformation at the piperidine core. Especially the piperidine ring of 3a and the 4-substituted piperidine ring of 3d show very similar properties, and therefore the difference in yield could not be explained by the calculated geometries of these starting materials. A more conclusive result could have been obtained by calculating the corresponding Ru complexes formed during the reaction. However, since the nature of the active catalyst species is not known entirely, no such calculations could be conducted.Fig. 1

Bottom Line: A Ru-catalyzed mono-arylation in α-position of saturated cyclic amines is reported employing a C-H activation protocol.Substitution of the pyridine directing group with a bulky group, e.g., trifluoromethyl in the 3-position, proved to be crucial to avoid bis-arylation.Additionally, the directing group can be cleaved, taking advantage of an unprecedented detrifluoromethylation reaction.

View Article: PubMed Central - PubMed

Affiliation: Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9/163-OC, 1060 Vienna, Austria.

ABSTRACT

Abstract: A Ru-catalyzed mono-arylation in α-position of saturated cyclic amines is reported employing a C-H activation protocol. Substitution of the pyridine directing group with a bulky group, e.g., trifluoromethyl in the 3-position, proved to be crucial to avoid bis-arylation. This highly selective transformation can be performed with different amines and arylboronate esters. Additionally, the directing group can be cleaved, taking advantage of an unprecedented detrifluoromethylation reaction.

No MeSH data available.


Related in: MedlinePlus