Kinetic Resolution of Axially Chiral 2,2‘-Dihydroxy-1,1‘-biaryls by Palladium-Catalyzed Alcoholysis

Abstract

Palladium-diamine complexes catalyzed kinetic resolution of axially chiral 2,2'-dihydroxy-1,1'-biaryls by alcoholysis of vinyl ethers. The reaction proceeded with high selectivity for various kinds of biaryls. This process is applicable to not only binaphthols but also biphenols, which have been considered to be difficult for the enantioselective synthesis by known catalytic methods.

Highly Enantioselective Oxidative Couplings of 2-Naphthols Catalyzed by Chiral Bimetallic Oxovanadium Complexes with Either Oxygen or Air as Oxidant

“…7 Kinetic resolution of BINOL derivatives by palladium-catalyzed alcoholysis has very recently been developed as an alternative method to approach optically active binaphthols and biphenols. 8 The use of a chiral pool method to prepare optically active BINOLs has also been investigated; however, it suffers from the stoichiometric amounts of chiral sources as chiral resolution does. 9 In sharp contrast to well-developed catalytic synthesis of racemic BINOLs, the asymmetric catalytic preparation of chiral binaphthols develops much more slowly.…”

Highly atom efficient catalytic reactions utilizing water and alcohols as reagents

“…Although an alcoholysis of vinyl ethers, so-called transvinylation reactions [5], was a traditional organic transformation, no asymmetric version was reported. The first example of asymmetric transvinylation was achieved by using Pd(OAc) 2 to avoid the side reactions caused by strong acid liberated from the catalyst precursors (Scheme 2) [6]. A bulky ligand contributed to not only construction of an asymmetric environment but also suppression of formation of Pd black [7].…”

Novel Bis(1,3,2-diazaphospholidine) Ligands for Asymmetric Catalysis

“…For instance, the group of Tsuji has described an efficient Pd catalyst based on secondary aryl diamines with chiral backbones. 9 On the other hand, Pfaltz and coworkers have described highly enantioselective Ir phosphineoxazoline catalysts containing N-aryl diazaphospholidine fragments. 10 In this contribution we describe the synthesis of the first bis-1,3,2-diazaphospholidine ligands bearing N-aryl substituents, along with preliminary catalytic results which include a highly enantioselective hydrogenation reaction.…”

“…[9][10][11] Among the latter phenyl (1a) and p-tolyl (1b) diamines, were selected as representative examples and reacted with commercially available tetrachlorodiphosphines, in the presence of an excess of NEt 3 (Scheme 1). These reactions provide a family of bis-1,3,2-diazaphospholidines 2-4, which differ in the nature of the backbone.…”