A Scalable Synthesis of Chiral Himbert Diene Ligands for Asymmetric Catalysis

Abstract

Chiral dienes are important ligands in asymmetric catalysis but they are less accessible than other commonly used ligands such as chiral bisphosphines. Here, we show that intramolecular [4 + 2] cycloaddition of a simply attained chiral allenecarboxanilide readily affords pseudoenantiomeric bicyclo[2.2.2]octa-2,5dienes containing an alkenyl bromide, which can be readily functionalized to give diverse chiral diene ligands. The synthesis is straightforward and easily conducted on multigram scales. These ligands exhibit high performance in nine types of enantioselective Rh(I)-catalyzed 1,4-addition or 1,2-addition reactions.

Asymmetric synthesis of P-stereogenic phosphindane oxides via kinetic resolution and their biological activity

“…>20:1 dr, up to 99% ee up to >99% ee i i i conjugate arylation product 3aa (3aa:3aaʹ > 20:1) with 73% ee, and the phosphindole oxide 1a was recovered with 98% ee. Encouraged by this promising result, we examined a series of chiral dienes for this reaction, and the readily available amide-dienes 51,52 proved to be the most effective (entries 5-10). All the examined amide-dienes could maintain the excellent regioselectivity (>20:1), and good selectivity was generally achieved (selectivity factor s > 50 for most cases).…”

Remote Enantioselective Epoxidation Reactions Catalyzed by Chiral Iron Porphyrin Complexes with a Hydrogen-Bonding Site

“…The reactive ethylene unit is three to five carbon atoms from the lactam binding site depending on the length of the tether. The first set of substrates was not further substituted at the olefin and the compounds were synthesized from 4-bromoquinolone 16 by Suzuki cross-coupling 17 (compound 2a) or from commercially available 4-methylquinolone by alkylation 18 (compounds 2b and 2c). In all epoxidation reactions, iodosobenzene was used as the stoichiometric oxidant in a 1:1 ratio relative to the substrate.…”