Highly Enantioselective Rhodium‐Catalyzed Asymmetric 1,4‐Addition Reactions of Arylboronic Acids to Acyclic α,β‐Unsaturated Compounds: The Formal Synthesis of (−)‐Indatraline

Abstract

H 4 )], [1] also known as the Zeise salt, in 1827, considerable numbers of olefin-coordinated transition-metal complexes have been synthesized for extensive use in organometallic and organic chemistry.[2]They also serve as useful precatalysts in the field of asymmetric catalysis. The labile olefins are rapidly and quantitatively replaced by optically active ligands that bear heteroatoms, such as nitrogen and phosphorus, which exhibit a stronger binding affinity towards metal atoms than the olefins, efficiently enabling the in situ generation of chiral catalysts.[3] However, the utilization of optically active olefin ligands as chiral modifiers had not received much attention until the independent studies of Hayashi et al. [4] and Carreira et al. [5] Their discoveries have demonstrated that chiral dienes with the appropriate geometry can form reasonably stable metal complexes due to chelation effects. These chiral diene-metal catalysts, particularly the rhodium complexes, have since been tested in catalytic asymmetric carboncarbon bond-forming reactions and were found to exhibit higher catalytic activities and enantioselectivities than phosphine ligands.[6] Since then, the design, synthesis, and investigation of chiral dienes for a wide range of asymmetric transformations has attracted much attention among synthetic organic chemists. [7, 8]

Design and Synthesis of Chiral Diene Ligands for RhI‐Catalyzed Enantioselective Arylation of N‐DPP‐protected Aldimines: Synthesis of the Antifungal Agent Bifonazole

“…Boronic acids 2 that were commercially available were used as supplied and/or were prepared using methods reported in the literature . Chiral diene ligands L1 were prepared according to the reported procedure …”

“…The preparation of ligand family L4 began with diketone 4 (Scheme ). Monotriflate 5 was observed as the major regioisomer (13:1) in 83 % yield when diketone 4 was treated with KHMDS (potassium hexamethyldisilazide) and Comins’ reagent at −78 °C; the sterically encumbered nature around the quaternary stereogenic center at C1 presumably prohibits deprotonation at C6.…”

Rh-catalyzed asymmetric 1,4-addition reactions to α,β-unsaturated carbonyl and related compounds: an update

“…170 Recently a Rh-catalyzed stereoselective 1,4-addition of sodium tetra-arylborates in the presence of chiral diene ligand (R)-L30, 171,172 was achieved as depicted in Scheme 80. Highly effective stereoselective catalysis has also been accomplished to generate a quaternary carbon stereogenic center with a chiral tetrafluorobenzobarrelene as the ligand.…”

Direct Synthesis of Chiral 3‐Arylsuccinimides by Rhodium‐Catalyzed Enantioselective Conjugate Addition of Arylboronic Acids to Maleimides

“…Previously we reported the design and synthesis of a novel family of chiral 2,5‐diarylbicyclo[2.2.1]diene ligands, prepared from inexpensive (−)‐bornyl acetate,13a, b that proved effective in a range of rhodium‐catalyzed enantioselective addition reactions useful for the preparation of the synthetic intermediates of biologically active compounds 13. These dienes exhibited not only a greater stability than their analogues derived from norbornadiene,14 but also induced high enantioselectivity and catalytic activity in the presence of low loadings of Rh I (TON up to 2000)13b in the 1,4‐addition of organoboronic acids to linear6b, 13b, g and cyclic13c α,β‐unsaturated carbonyl compounds, and nitroolefins 13d. We have also shown these ligands to be effective in Rh I ‐catalyzed 1,2‐addition reactions 13e.…”