Heterogeneously Catalyzed Asymmetric Hydrogenation of C═C Bonds Directed by Surface-Tethered Chiral Modifiers

Abstract

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1-Naphthylamine functionalized Pt nanoparticles: electrochemical activity and redox chemistry occurring on one surface

“…The hydrogen under potential deposition (H UPD , ca. 34 The isolation of free Pt sites by the ligands is in agreement with the absence of any catalytic CO oxidation activity. In addition, no CO oxidation was detected during a CO stripping cycle, so it can be assumed that the complete Pt surface is blocked and no ECSA can be determined for fresh NA-Pt NP samples.…”

Influence of Adsorption Geometry in the Heterogeneous Enantioselective Catalytic Hydrogenation of a Prototypical Enone

“…This conclusion that adsorption is non-dissociative is strongly confirmed by the NEXAFS data presented in Figure 2. In our earlier work 11 we proposed a mechanism for the asymmetric hydrogenation of isophorone (1) which involved interaction between the secondary amine of the chiral modifier 2 and the ketone functionality of the enone to yield an iminium species (4) (or enamine) as the reaction intermediate (Scheme 2). In keeping with this we found that, when used as the chiral agent, a tertiary amine analogue of 2 which prevents formation of such an intermediate gave only racemic product.…”

Aspects of Heterogeneous Enantioselective Catalysis by Metals

“…This goal has now been achieved 79 by purposeful synthesis of chiral ligands that contain the 400 characteristic pyrrolidine motif present in proline, anchor robustly to the metal surface, resist 401 displacement and direct the heterogeneously-catalyzed enantioselective hydrogenation of isophorone, as 402 described below. 403…”

“…79 Each 404 contained a sulfur atom in order to achieve covalent tethering to the metal surface. The result of using 405 these chiral sulfide ligands as chiral modifiers in the Pd/C-catalyzed hydrogenation of isophorone is 406 summarized in Figure 7, which shows the measured e.e.…”