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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.


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Mentions: We propose the following mechanism for cleavage of the trifluoromethyl group (Scheme 4): Substrate 16 reacts with a free O–H group at the surface of silica gel to form 17, and the triflouromethyl group is bound to silica gel. Next, water present in silica gel hydrolyzes the newly formed O–CF3 bond and trifluoromethanol is released, which then decomposes to carbonyl difluoride and hydrogen fluoride rapidly. This decomposition is described in the literature [41] to occur already at −20 °C, leading to gaseous compounds which can then not be detected using standard analytic techniques. The formation of gaseous compounds is supported by infrared (IR) analysis of the remaining silica gel after the deprotection, where no bands specific for C–F bonds were detected.


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)

© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Mentions: We propose the following mechanism for cleavage of the trifluoromethyl group (Scheme 4): Substrate 16 reacts with a free O–H group at the surface of silica gel to form 17, and the triflouromethyl group is bound to silica gel. Next, water present in silica gel hydrolyzes the newly formed O–CF3 bond and trifluoromethanol is released, which then decomposes to carbonyl difluoride and hydrogen fluoride rapidly. This decomposition is described in the literature [41] to occur already at −20 °C, leading to gaseous compounds which can then not be detected using standard analytic techniques. The formation of gaseous compounds is supported by infrared (IR) analysis of the remaining silica gel after the deprotection, where no bands specific for C–F bonds were detected.

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