Effects of Extended Aryl‐Substituted Bisoxazoline Ligands in Asymmetric Synthesis – Efficient Synthesis and Application of 4,4′‐Bis(1‐Naphthyl)‐, 4,4′‐Bis(2‐Naphthyl)‐ and 4,4′‐Bis(9‐Anthryl)‐2,2′‐isopropylidenebis(1,3‐oxazolines)

Abstract

Keywords: Asymmetric catalysis / Ligand design / Bisoxazoline ligands / Non-proteinogenic amino acids / Chiral Lewis acidsThe steric influence of extended aryl substituents on 2,2Ј-bis(1,3-oxazoline) ligands was investigated in a series of asymmetric catalytic reactions such as Mukaiyama aldol and Michael reactions, hetero-Diels-Alder processes, and allylic alkylation reactions. 4,4Ј-(2-Naphthyl)-and 4,4Ј-(9-anthryl)-

Kinetic Resolution of Racemic α-Arylalkanoic Acids with Achiral Alcohols via the Asymmetric Esterification Using Carboxylic Anhydrides and Acyl-Transfer Catalysts

“…New catalysts, ( S )-α-Np-BTM and ( S )-β-Np-BTM used in entries in 9 and 10, were easily generated from 2-amino-2-(α-naphthyl)-1-ethanol and 2-amino-2-(β-naphthyl)-1-ethanol, respectively. These amino alcohol derivatives had already been utilized for the synthesis of chiral ligands, which were applied to the asymmetric cyclopropanation of 2,5-dimethyl-2,4-hexadiene to produce several chrysanthemic acid derivatives including pyrethroid chemicals. Other benzotetramisole-type catalysts, such as ( S )- i -Pr-BTM, ( S )- t -Bu-BTM, and ( S )-Bn-BTM, were prepared from the corresponding 1,2-amino alcohols or α-amino acids according to the synthetic protocol reported by Birman et al…”

Synthesis of 1-Oxadecalins from Anisole Promoted by Tungsten

“…The oxidation of 24 with CuBr 2 in CH 3 CN led to the recovery of the bicyclic enone 25 in 50% yield (Scheme 4). The presence of air during the oxidation was found to cause a significant The preparation of a chromen from an arene appears to be without precedent, but the aromatic chroman system is routinely synthesized from phenol [15][16][17][18][19][20] or other substituted benzene 21,22 precursors as outlined in Scheme 5. [23][24][25][26][27][28][29][30] Chromans have also been prepared from fluorobenzenes using {Cr(CO) 3 } 31 and [Rh(C 5 EtMe 4 )Cl 2 ] 2 32 to promote the aromatic substitution.…”

Copper Catalyzed Enantioselective Intramolecular Aminooxygenation of Alkenes

“…An early screen of commercially available bisoxazoline ligands revealed that the 5-phenyl substitution pattern is essential. Other aryl substituents such as 2-naphthalene,8 as well as cis and trans 4,5-disubstituted phenyl bisoxazoline derivatives9 were also examined. When used in slight excess, both antipodes of the 4,5- cis -diphenyl bisoxazoline ligand were optimal (entries 5 and 6).…”