Asymmetric Suzuki–Miyaura Coupling in Water with a Chiral

Palladium Catalyst Supported on an Amphiphilic Resin

Yasuhiro Uozumi

Angew. Chem. Int. Ed. 2009, 48, 2708 –2710

(a) Avoiding cis/trans isomerizations after the oxidative addition step(b) Limited flexibility around N-N bonds, providing an adequate chiral environment and a c

onsiderable steric crowding beneficial for the formation of the 14e Pd(0) catalysts and the for reductive elimination step

Rosario Ferna´ndez J. AM. CHEM. SOC. 2008, 130, 15798–15799

Rosario Ferna´ndez J. AM. CHEM. SOC. 2008, 130, 15798–15799

Rosario Ferna´ndez J. AM. CHEM. SOC. 2008, 130, 15798–15799

a Isolated yield. b Conditions: (A) excess 2 (1.5 equiv); (B) excess 1(2.5 equiv). e The absolute configuration was assigned by comparison with literature data: see ref 6h. g Reaction performed in 1 mL of solvent. h The absolute configuration was assigned after demethylation to the 1-(biphenyl-2-yl)naphthalen-2-ol derivative and comparison of the optical rotation with the reported value.

J. Am. Chem. Soc. 2001, 123, 2919-2920

• Tetra-n-butylammonium fluoride or TBAF is a quaternary ammonium salt with the chemical formula (CH3CH2CH2CH2)4N

+F-.

• In the laboratory the compound is usually encountered in the latter form as a source of organic-soluble fluoride ion to remove silyl ether protecting groups. It is also used as a phase transfer catalyst and as a mild base.

[a] Reactions were carried out in water at 80oC for 24 h with the reaction components in the following ratio: 1 (mol)/2 (mol)/TBAF (mol)/Pd-(OAc)2 (mol)/PS–PEG–L* (mol of P)/H2O (L)=1 : 5 : 10 : 0.1 : 0.1 : 20.

[b] Yield of the isolated product. [c] The ee value was determined by HPLC (chiralpak OD-H or AD-H). The absolute configuration is shown in parenthesis. [d] After crystallization

Conclusions• The highly enantioselective Suzuki–Miyaura biaryl coupling

was carried out in water for the first time with a recyclable palladium complex of a chiral imidazoindole phosphine ligand supported on an amphiphilic PS–PEG resin.

• In this article, the asymmetric Suzuki–Miyaura coupling for the synthesis of a variety of axially chiral biaryl compounds with high stereoselectivity (up to 94%ee).