Carbometalated Complexes Possessing Tripodal Pseudo-C₃-Symmetric Triptycene-Based Ligands

Abstract

New air-stable tripodal triphosphine ligands 1,8,13-tris-(diisopropylphosphino)-2,3-dimethoxytriptycene (P 3 T1) and 1,8,13-tris-(diphenylphosphino)-2,3-dimethoxytriptycene (P 3 T2) are presented and discussed. Their synthesis is based on the first practical synthesis of 1,8,13-tribromotriptycene. Reaction with palladium leads to the formation of new pseudo-C 3 -symmetric carbometalated complexes: namely, Pd(P 3 T1)Cl and Pd(P 3 T2)Cl. The catalytic activity of the new ligands and complexes was tested in the palladium-catalyzed chemoselective transfer hydrogenation of α,β-unsaturated ketones.

Synthesis of Distorted 1,8,13‐Trisilyl‐9‐hydroxytriptycenes by Triple Cycloaddition of Ynolates to 3‐Silylbenzynes

“…Triptycene is a rigid and symmetric propeller shaped organic molecule with a bicyclo[2.2.2]octatriene skeleton . Because of these special properties, triptycenes have been used as basic units of host molecules in the field of molecular recognition, supramolecular chemistry, macromolecules, material sciences, and metal ligands . However, functionalized triptycenes are not easily obtained because major synthetic methods for triptycenes are limited to cycloaddition of benzyne or benzoquinone to anthracenes.…”

“…[1] Because of these special properties,t riptycenes have been used as basic units of host molecules in the field of molecularr ecognition, [2] supramolecular chemistry, [3] macromolecules, [4] materials ciences, [5] and metal ligands. [6] However, functionalized triptycenes are not easily obtained because major synthetic methodsf or triptycenes are limited to cycloaddition of benzyne [7] or benzoquinone [8] to anthracenes. Thus, it is difficult to prepare these startingm aterials with specific substituents.…”

Triptycene Derivatives: From Their Synthesis to Their Unique Properties

“…In 2018, Kisets et al presented a successful synthetic route towards 1,8,13-halogenated triptycenes and corresponding triphosphine ligands [ 149 ]. The method facilitates efficient synthesis of 1,8,13-tribromotriptycene derivative in two steps, starting with the Diels–Alder reaction of 1,8-dibromoanthracene towards 1,13-dibromo-6,7-dimethoxytriptycene ( Scheme 9 ).…”

“… The first applicable synthesis of 1,8,13-tribromotriptycene. Phosphination and bridgehead carbon atom metalation gives triptycene-based complexes of Pd(II), which act as catalysts for chemoselective transfer hydrogenation of α,β-unsaturated ketones (R = i -Pr; Ar = Ph, 4-MeO-phenyl, 1-naphthyl, 2-furyl) [ 149 ]. …”

Well‐defined Nickel P3C Complexes as Hydrogenation Catalysts of N‐Heteroarenes Under Mild Conditions

“…Inspired by previous reports, we hypothesized that the electronic flexibility of the trigonal‐bipyramidal P 3 C complexes combined with an appropriate rigidity and bulkiness could serve to develop hydrogenation catalysts. To the best of our knowledge, these are the first complexes reported based on a 1 st row transition metal with P 3 C ligands active for the catalytic hydrogenation reaction [5a] …”