2,8'-disubstituted-1,1'-binaphthyls: a new pattern in chiral ligands.
The title binaphthyls 19 and 26, which are the positional isomers of 2-methoxy-2'-(diphenylphosphino)-1,1'-binaphthyl (MOP, 19) and 2-amino-2'-hydroxy-1,1'-binaphthyl (NOBIN, 26), have been synthesized by Suzuki coupling as the key step (10 + 15-->18), followed by functional group transformations, involving C-P and C-N bond formation (18-->19 and 18-->23). Racemic intermediate 22 was resolved by co-crystallization with N-benzylcinchonidinium chloride and the absolute configuration determined by X-ray crystallography. These novel binaphthyls are configurationally stable and, as such, potentially usable as chiral ligands in asymmetric reactions. Michael addition of the glycine-derived enolate 40 to methyl acrylate, carried out in the presence of (R)-(-)-27 as the chiral phase-transfer catalyst, afforded L-glutamic acid (S)-(+)-43 of 92% ee (after hydrolysis of the primary product).
Vyskocil
Stĕpán
S
Department of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK. stepanv@natur.cuni.cz
Meca
Ludĕk
L
Tislerová
Iva
I
Císarová
Ivana
I
Polásek
Miroslav
M
Harutyunyan
Syuzanna R
SR
Belokon
Yuri N
YN
Stead
Russel M J
RM
Farrugia
Louis
L
Lockhart
Stephen C
SC
Mitchell
William L
WL
Kocovský
Pavel
P