Efficient Synthesis of Chiral 1,1′‐Binaphthalenes by the Asymmetric Suzuki–Miyaura Reaction: Dramatic Synthetic Improvement by Simple Purification of Naphthylboronic Acids

Abstract

Naphthylboronic acids prepared as reported in the literature are contaminated with HCl. A very simple purification prior to their use in Suzuki-Miyaura couplings has been found to be crucial, rendering efficient some reactions that had been reported in the literature either to fail or to give extremely poor yields. With this improvement, parent boronic acids can be used instead of esters at moderate temperatures, and bromo derivatives can be used instead of iodo derivatives. Convenient access to chiral sterically hindered binaphthalene derivatives has been achieved through the use of boronic acids, bromonaphthalenes, and ferrocenylphosphane ligands. The products were obtained in good yields (95-55 %) and with good enantioselectivities (90-50 %). Bulkier ligands are less efficient in the coupling of hindered partners.

Asymmetric Suzuki–Miyaura Coupling in Water with a Chiral Palladium Catalyst Supported on an Amphiphilic Resin

“…[3,4] Recently, Bermejo et al reported a novel asymmetric catalytic system that promotes the SuzukiMiyaura biaryl coupling with excellent enantioselectivity. [5] Although pioneering strides have been made, the development of highly enantioselective catalyst systems with wide substrate tolerance and acceptable catalytic activity still remains a major challenge.…”

Synthesis of axially chiral biaryl compounds by asymmetric catalytic reactions with transition metals

“…In order to provide an alternative to the rather sensitive boronic esters, they reported a purification procedure of naphthylboronic acids [98] that improved dramatically the efficiency of the catalytic reactions (from traces of coupling products before purification to up to 95% yield) under the same conditions than those reported by Cammidge et al [50]. During this study, precursor was also looked into.…”

“…Scheme 3.20 -Asymmetric biaryl coupling with ligands 2, 31 and 32[98]. Scheme 3.24 -Heterogeneous asymmetric biaryl coupling in water[106].Scheme 3.26 -Asymmetric biaryl coupling with ligands 45a-c [109].Scheme 3.28 -Dynamic asymmetric Suzuki coupling with ligand 52[48].…”

Synthesis of polysaccharide derivatives bearing bromobenzoate pendants for use as chiral auxiliaries

“…2-Bromo-3-methylbenzoyl chloride and 4-bromo-3-methylbenzoyl chloride were prepared through the reaction of the corresponding carboxylic acids with oxalyl chloride in toluene. The regioselectively protected cellulose derivative CeATr [54], 2-methylnaphthalen-1-ylboronic acid 8a [55], and 2-methoxylnaphthalen-1-ylboronic acid 8b [55] were prepared according to literature procedures.…”