Highly Enantiomerically Enriched Planar Chiral Naphthalene Tricarbonylchromium Complexes

Abstract

Lithiation/electrophile trapping reactions were carried out with the highly enantiomerically enriched complex [Cr(5-bromonaphthalene)(CO)3]. Electrophile quenching with ClPPh2, PhCHO, and (Me3SiO)2 afforded the enantiomerically enriched (>97% ee) planar chiral 5-substituted naphthalene complexes with PPh2, CH(Ph)OH, and OH substituents, respectively. Very mild Pd-catalyzed Suzuki-Miyaura cross-coupling reactions were developed and applied to the highly labile [Cr(5-bromonaphthalene)(CO)3] to give nine new planar chiral aryl-, heteroaryl-, alkynyl-, and alkenylnaphthalene chromium complexes with high enantiomeric purity. The efficient ambient-temperature coupling reactions with borinates prepared in situ were also applied to a number of chlorobenzene complexes and to aryl and vinyl halides.

An Efficient Entry to Planar Chiral Organometallic Complexes via Pd-Catalyzed Asymmetric Hydrogenolysis

“…[13] This chemistry is currently being extended to asymmetric C-C and C-P bond forming processes in our laboratory.…”

Cross‐Coupling Reactions to sp Carbon Atoms

“…The qualification of the Suzuki-Miyaura protocol to provide very mild conditions for Pd-catalyzed cross-couplings to C(sp) atoms has impressively been demonstrated in a case study by Kündig et al [317]. In their work, a series of novel chiral alkynylnaphthalene Cr(0) complexes 117 have been synthesized from the parent bromo derivative 118 (Scheme 9.43).…”

“…in Et 2 O (2.5 ml) by treatment with nBuLi (1.6 M in hexanes, 0.62 ml, 1.00 mmol, 2 equiv.) at −78 • C for 30 min (Scheme 9.43) [317]. To the mixture was added dropwise 9-MeO-BBN (1.0 M in hexanes, 1.0 ml, 1.00 mmol, 2 equiv.)…”

“…Scheme 9.43 Planar chiral alkynylnaphthalene Cr(0) complexes 117 by a base-free Suzuki-Miyaura reaction[317].…”

Catalysis: J. M. Thomas honored / Organic Chemistry: E. P. Kündig awarded

“…Examples include the asymmetric synthesis of alicyclic compounds via arene metal complexes, planar chiral arene complexes, COemulating chiral ligands and their application in asymmetric synthesis, and new chiral 1,3-aminophenols as auxiliaries and building blocks for ligands. He recently reported on highly enantiomerically enriched planar chiral naphthalene tricarbonylchromium complexes in Chemistry-An Asian Journal [5] and on catalyzed Diels-Alder reactions between dienes and a,b-unsaturated ketones in Chemistry-A European Journal. [6] …”