Novel Chiral Bidentate 5-Cyclopentadienylphosphine Ligands: Their Asymmetric Induction at the Ruthenium(II) Center and Application in Catalysis

Abstract

The syntheses of four classes of novel ruthenium(ii) complexes with chiral bidentate cyclopentadienylphosphine ligands and their application in asymmetric catalysis are described. This approach to an enantioselective reconstitutive condensation was assisted by molecular modeling to deal with the question of asymmetric induction at the metal center and lead to a more precise understanding of the enantiodiscriminating step. The catalysts were routinely tested towards the enantioselective reconstitutive condensation of ethyl undecynoate and cyclohexyl-2-propen-1-ol to provide ethyl 12-cyclohexyl-11-oxo-13-tetradecenoate.

Chelate Complexes of Functionalized Cycloheptatrienyl Ligands: 17- and 18-Electron Molybdenum Complexes with Linked Cycloheptatrienyl−Phosphane Ligands and Their Use in Transition Metal Catalysis

“…of n-butyllithium followed by addition of 2-cyclopentenone. [19] Similarly, one should be able to obtain the related cycloheptatrieneϪphosphane ligand precursor 2 (Scheme 1) by addition of 2-(diphenylphosphanyl)phenyllithium [22] to the tropylium cation C 7 H 7 ϩ . [23] In fact, careful monolithiation of 1,2-dibromobenzene and reaction with ClPPh 2 led to 2-BrC 6 H 4 PPh 2 (1), [22,24] which was successively treated with nBuLi and (C 7 H 7 )BF 4 to afford the air-stable ligand precursor [2-(cyclohepta-2,4,6-trienyl)phenyl]diphenylphosphane (2) in large quantities.…”

Fused Dihydrodibenzobarrelene (Dibenzobicylco[2.2.2]octadiene) and Lactone Rings via Tandem Diels‐Alder and Condensation Reactions of Dialkyl Fumarates and 9‐Anthracenemethanol

“…It has been well established that when in combination with a suitable dienophile, anthracenes will readily undergo Diels‐Alder reactions to form bicyclic compounds . Once formed, these structures can undergo several reactions via either chemical substitution, photoisomerization, or photorearrangement to form a variety of different structures . One such example of these complex structures that can undergo secondary reactions to form further complex multicyclic structures, is bicyclic adducts with a fused lactone ring.…”

Experimental Protocols

“…The present protocol thus represents the adaptation of this catalytic system for the microwave reactor, which enables a 20-fold reduction in reaction time [1]. 6 Literature [19] Background The pentacyclic adduct of maleic anhydride and anthracene has been achieved under conventional reflux conditions [18]. The current procedure adapts the reported protocol to the microwave reactor, reducing the reaction time from 2 h to 5 min [19].…”

“…18 Reagents and hazard information for the Hantzsch library synthesis. skin irritation; may be harmful if absorbed through the skin; may cause eye irritation; may be harmful if inhaled; material may be irritating to mucous membranes and upper respiratory tract; may be harmful if swallowed…”