Bis-quaternary cinchona alkaloid salts as asymmetric phase transfer catalysts
View Patent ↗The invention is directed to novel bis-quarternary cinchona alkaloid salts and the use of bis-quarternary cinchona alkaloid salts in asymmetric phase transfer catalysis. The present invention is directed to novel bis-quarternary cinchona alkaloid salts and the use of bis-quarternary cinchona alkaloid salts in asymmetric phase transfer catalysis. On certain substrates and under specific reaction conditions, the inventors have discovered that the use of bis-quarternary cinchona alkaloid salts in asymmetric phase transfer catalysis surprisingly provides for a more active and efficient process as compared to mono-quarternary catalysts.
1. A bis-quaternary alkaloid salt having the chemical structure of Formula II:
wherein:
R 1 is ethyl or vinyl;
R 2 is hydrogen or methoxy;
Ar 1 and Ar 2 are defined as follows:
I) Ar 1 is:
and Ar 2 is allyl; or
(II) Ar 2 is:
Ar 1 is:
(II) Ar e is:
Ar 1 is:
or —CH 3 ; and,
X and Y are independently a halide anion.
2. A bis-quaternary alkaloid salt of claim 1 having the structure of Formula IIa
wherein R 1 is vinyl or ethyl, R 2 is —H or MeO—, and X and Y are independently a halide.
3. The bis-quaternary cinchona alkaloid salt of claim 2 wherein R 1 is vinyl and R 2 is methoxy.
4. The bis-quaternary cinchona alkaloid salt of claim 3 wherein X and Y are independently Br or I.
5. A bis-quaternary alkaloid salt having the structure:
wherein:
R 2 is
R 3 is
R 4 is
X − is
Y − is
OMe
Br
Br;
H
Br
Br;
H
I
I;
H
Br
I;
H
Br
Br;
H
Me
Br
I; or
H
Allyl
Br
Br;
has the structure.
6. The bis-quaternary alkaloid salt of the Formula: