Single‐Face/All‐cis Arene Hydrogenation by a Supported Single‐Site d⁰ Organozirconium Catalyst

Abstract

The single-site supported organozirconium catalyst Cp*ZrBz2 /ZrS (Cp*=Me5 C5 , Bz=benzyl, ZrS=sulfated zirconia) catalyzes the single-face/all-cis hydrogenation of a large series of alkylated and fused arene derivatives to the corresponding all-cis-cyclohexanes. Kinetic/mechanistic and DFT analysis argue that stereoselection involves rapid, sequential H2 delivery to a single catalyst-bound arene face, versus any competing intramolecular arene π-face interchange.

Selective Arene Hydrogenation for Direct Access to Saturated Carbo‐ and Heterocycles

“…Recently,t he Marks group disclosed ac atalyst system that exclusively delivers the cis isomer. [17] Theg roup had previously reported on supported, singlesite [18] organozirconium catalysts which consist of ac ationic Cp*Zr(alkyl) 2 (Cp* = C 5 Me 5 )p recatalyst tethered to an anionic sulfated zirconiumoxide support. [19] Thed ifferent selectivities of the new Cp*Zr(benzyl) 2 precatalyst (13) compared to the previous single-site Cp*ZrMe 2 /ZrS precatalyst (12)w ere demonstrated with the hydrogenation of hexadeuterobenzene (9; Figure 2A).…”

Accessing Difluoromethylated and Trifluoromethylated cis‐Cycloalkanes and Saturated Heterocycles: Preferential Hydrogen Addition to the Substitution Sites for Dearomatization

“…With chiral iridium catalysis, the group of Zhou achieved the enantioselective hydrogenation of fluorinated isoquinolines . Considering that di‐ or trifluoromethylated arenes and heteroarenes bearing diverse functional groups are either readily prepared or commercially available, we recognized that a straightforward synthetic route, subjecting these compounds to hydrogenation, could provide access to di‐ and trifluoromethylated cycloalkanes and saturated heterocycles with high atom efficiency. Herein, we describe a synthetic strategy for the convenient and diastereoselective synthesis of equatorially di‐ and trifluoromethylated cis ‐cycloalkane and saturated heterocycle building blocks, by the straightforward reduction of di‐ and trifluoromethyl arenes and heteroarenes, respectively, in a manner that enables preferential addition of hydrogen to the substitution sites for dearomatization (Figure c).…”

Die selektive Arenhydrierung bietet einen direkten Zugang zu gesättigten Carbo‐ und Heterocyclen

“…Zu solchen Katalysatorsystemen zählen homogene Metallkomplexe und heterogene Katalysatoren wie Metall-Nanopartikel und trägerfixierte Katalysatoren. [ [17] Die Gruppe hatte zuvor über trägerfixierte [18] Organozirconiumkatalysatoren berichtet, die aus einem kationischen Cp*Zr(Alkyl) 2 -Präkatalysator (Cp* = C 5 Me 5 )b estehen, der an einen anionischen sulfatisierten Zirconiumoxidträger gebunden ist. Die Entwick-lung von Transformationen mit vorhersagbarer Selektivität bleibt anspruchsvoll, und die Erforschung solcher Reaktionen ist ein aufstrebendes Gebiet.…”

“…[16] 2. Stereoselektive Arenhydrierung [17] Die Gruppe hatte zuvor über trägerfixierte [18] Organozirconiumkatalysatoren berichtet, die aus einem kationischen Cp*Zr(Alkyl) 2 -Präkatalysator (Cp* = C 5 Me 5 )b estehen, der an einen anionischen sulfatisierten Zirconiumoxidträger gebunden ist. [19] Die unterschiedliche Selektivitätd es neuen Cp*Zr(Benzyl) 2…”